Important Corrections to the Documentary Transcript

The victim’s name was Shannon Mohr, sometimes referred to after her marriage as Shannon Mohr Davis. The transcript repeatedly calls her Shannon Moore, Shanna and, near the end, Diane.

Shannon died on July 23, 1980, at the age of 25. She had married David Richard Davis in Las Vegas on September 24, 1979, approximately seven weeks after meeting him. She died one day before their ten-month wedding anniversary.

The case was not solved through one ordinary toxicology test. Shannon’s body was exhumed, tissue samples produced an unidentified chromatographic result, scientists developed and refined a procedure to analyze the material, and a second examination of her body located suspected injection sites containing high concentrations of succinylcholine.

The transcript also presents a detailed reconstruction in which Davis persuaded Shannon to have sex in the woods, injected her once unsuccessfully, struck her head against a rock and injected her again into a blood vessel. The prosecution argued that he injected and killed her with succinylcholine before staging the riding accident, but the published appellate decision does not establish every one of those dramatic actions as a directly observed fact.

Davis was indicted on October 13, 1981. He disappeared in December 1981 and remained a fugitive until January 6, 1989, when he was arrested in American Samoa after a television viewer helped identify him.

A Hillsdale County jury convicted Davis of first-degree murder on December 5, 1989. He was sentenced to life imprisonment without the possibility of parole. The Michigan Court of Appeals later affirmed the conviction.

Davis remained incarcerated until his death in a Michigan prison medical facility on November 9, 2014. He was 70 years old.

Shannon Mohr’s Early Life

Shannon Lou Mohr grew up in Toledo, Ohio, as part of a close and devout Catholic family.

She was the youngest of three children and remained particularly close to her parents, Robert and Lucille Mohr. Relatives remembered her as sociable, compassionate and emotionally generous.

Shannon chose nursing as her profession. The work suited the calm and caring personality described by the people who knew her.

By the summer of 1979, Shannon was 24 and still living near her family in Toledo. She wanted to marry and create a family of her own, but her romantic life had already included disappointment.

Accounts from relatives described at least two serious relationships that ended painfully. One man was not prepared to marry when Shannon was ready. Another reportedly proposed and allowed wedding preparations to begin before Shannon discovered that he was already married.

Those experiences appear to have left Shannon embarrassed and emotionally vulnerable. They may also help explain why David Davis’s immediate certainty, constant attention and willingness to marry seemed so attractive.

David Richard Davis Before Shannon

David Richard Davis was substantially older than Shannon.

He presented himself as a successful, adventurous and unusually accomplished man. According to contemporary reporting, he claimed that he had been orphaned, served as a wounded Vietnam veteran, played football at the University of Michigan and built a prosperous life through farming and business.

Investigators later found that many of those claims were false or exaggerated. His parents were alive, he had not lived the heroic military life he described, and his academic and athletic history did not match the image he sold to Shannon’s family.

Davis also concealed significant parts of his romantic and family history. He had previously been married and had children, despite representing himself to some women as an unattached man whose great earlier love had died tragically.

More important than the lies about his past was evidence showing that he had considered succinylcholine as a method of murder years before Shannon died.

During the mid-1970s, Davis dated a woman named Kay Kendall. The Michigan Court of Appeals later recorded that Davis told Kendall about a murder committed with succinylcholine, a muscle-paralyzing drug capable of causing death through respiratory failure.

Davis reportedly described killing someone with succinylcholine as the “perfect crime.”

In 1978, Davis created the identity David Meyer Bell and obtained a Florida driver’s licence under that name.

He proposed to Kendall, but she ultimately decided not to marry him. Their relationship ended in April 1979.

That same month, Davis began an intense relationship with another woman, Jeanne Hohman.

Within approximately one month, Davis and Hohman were discussing marriage. He suggested that they travel to Las Vegas for a ceremony, but she was reluctant to commit so quickly.

They discussed marriage again in July 1979. Hohman remained uncertain.

Davis soon turned his attention toward someone else.

The Wedding Where Shannon Met David

On August 4, 1979, Davis attended the wedding of Tom and Regina Davis.

Before the wedding, he asked Tom whether any single women would be present.

Shannon Mohr was one of the guests.

The two met during the reception and spent much of the evening together. Witnesses later described a rapid and intense attraction.

Davis appeared confident, humorous and attentive. He told stories that made him sound brave, successful and worldly.

Shannon saw a man who seemed eager to protect her, marry her and provide the stable future she wanted.

What Shannon did not know was that Davis’s relationship with Jeanne Hohman had not been resolved honestly.

Davis and Shannon began an intense courtship without Hohman knowing that he was developing a serious relationship with another woman.

The Seven-Week Courtship

Davis moved exceptionally quickly.

Within weeks, he proposed to Shannon.

To her relatives, his speed could be interpreted as romantic certainty. He acted as though he had recognized the woman he wanted to spend the rest of his life with and saw no reason to delay.

Shannon’s earlier disappointments may have made that decisiveness especially powerful. Instead of another man delaying marriage or hiding that he was unavailable, Davis appeared ready to commit immediately.

After approximately seven weeks together, Shannon and Davis traveled to Las Vegas.

They were married on September 24, 1979.

Shannon’s family would normally have expected a large Catholic wedding surrounded by relatives. The sudden Las Vegas ceremony was unusual for her, but they tried to support the marriage and welcome Davis into the family.

Shannon moved to Davis’s farm in rural Hillsdale County, Michigan, near the communities of Pittsford and Hudson.

She believed she was beginning the stable married life she had wanted for years.

The Insurance Policies

On October 2, 1979, only eight days after the wedding, Shannon and Davis purchased major life insurance policies.

Each policy had a face value of $110,000, and each spouse named the other as beneficiary. The policies included double-indemnity provisions that increased the payment if the insured person died accidentally.

Other contemporary reporting described a larger collection of six policies potentially worth more than $300,000. The difference reflects the way various reports counted the policies, accidental-death provisions and associated coverage.

The essential fact was clear: Davis stood to receive a substantial amount of money if Shannon died, particularly if her death appeared accidental.

Davis later told people that Shannon had no life insurance.

That statement was false.

The Secret Relationship With Jeanne Hohman

Approximately one week before marrying Shannon, Davis told Jeanne Hohman that he would not be able to see her normally for about a year.

He claimed he was involved in dangerous government work that he could not explain.

Davis warned Hohman that it might appear publicly as though he had married someone else. He told her to disregard anything she might read about him in newspapers.

Hohman believed that Davis was carrying out a secret government assignment.

Approximately one month after the Las Vegas wedding, Davis resumed his relationship with Hohman without telling her that he had genuinely married Shannon.

Davis claimed the government would pay him about $250,000 for completing his secret assignment.

In June 1980, Hohman asked how much longer the supposed mission would continue.

Davis said it would last another three or four weeks.

Shannon died approximately one month later.

The amount Davis claimed he would receive for the imaginary government assignment was strikingly close to the amount he could collect from the life insurance coverage.

The prosecution later used these conversations to argue that Davis had planned Shannon’s death well in advance and had already prepared a false explanation for his temporary marriage.

Life on the Farm

After the wedding, Shannon settled into life on Davis’s farm.

The couple acquired two riding horses. Shannon was not considered a highly experienced rider and generally preferred moving at a slow pace.

Relatives and neighbours frequently joined or accompanied the couple during rides.

Shannon’s nephew sometimes stayed at the farm, and the couple’s dogs also commonly followed them.

From the outside, the new marriage appeared active and adventurous. Shannon had left the city environment of Toledo for the open land, horses and outdoor life Davis had promised.

Within months, however, comments Shannon made to relatives suggested that she might have been reconsidering how well she knew her husband.

According to family accounts, she advised a younger relative to learn everything possible about a future husband’s family, employment and views before getting married.

The comments may have reflected ordinary advice from a newly married woman. They may also have indicated that Shannon had begun discovering inconsistencies in Davis’s stories.

The Final Horseback Ride

On July 23, 1980, Shannon and Davis prepared to ride their horses.

Shannon’s nephew was staying at the farm with Shannon’s mother.

Although the nephew and the dogs often accompanied the couple, Davis did not allow them to come that day.

Davis and Shannon rode to the nearby home of Richard and his wife, the Brittons.

When the Brittons’ son expressed interest in joining the return ride, Davis refused, even though the boy had ridden with them before.

Those decisions ensured that Davis and Shannon would be alone when they entered the wooded area between the two farms.

After visiting the Brittons, Shannon and Davis rode away together.

Approximately 25 minutes later, Davis returned alone at high speed.

He was sweating, visibly excited and had blood on his shirt.

He told the Brittons that Shannon had fallen from her horse and was seriously injured.

Davis’s Accident Story

Davis said that he and Shannon had entered the woods in single file.

According to his account, he was riding ahead when he heard Shannon scream.

He turned and saw her lying on the ground near her horse.

Davis claimed she had apparently been thrown and struck her head against a large rock.

He said he moved her toward the edge of the woods before riding for help.

Richard Britton drove with Davis to the area.

Shannon was lying on the ground with her shoes removed and her blouse open. Her skin had developed a bluish-grey colour.

Davis checked her neck and said that she was still alive.

He and Britton placed Shannon in the vehicle and began the urgent drive toward the hospital.

Davis stayed beside her and attempted mouth-to-mouth resuscitation while Britton drove.

Shannon was pronounced dead after arriving at the hospital.

She was 25 years old.

Problems at the Scene

Police examined the wooded area where Davis claimed Shannon had fallen.

They found a partially buried rock stained with blood.

Shannon’s untied shoes were approximately eight feet away from the rock.

The shoes were eventually returned to Davis and were never located again.

The Brittons later returned to the area and noticed circular marks or bruising on two tree branches.

Horse manure was present several feet from each branch.

The observations suggested that the horses might have been tied in place rather than moving freely when Shannon was supposedly thrown.

Shannon’s blouse and shoes also raised questions.

Her clothing and position did not fit neatly with an ordinary fall from a slowly walking horse.

At the time, however, investigators did not have a clear alternative explanation.

The Head Injury

The initial explanation for Shannon’s death was a catastrophic injury caused by falling from her horse and striking the rock.

Later examination showed that she had suffered a relatively minor contrecoup injury, meaning the brain was damaged slightly on the side opposite the impact.

A neurological expert concluded that the injury did not cause Shannon’s death and may not even have rendered her unconscious.

The bloodied rock therefore helped make the scene look convincing, but the head injury could not explain why Shannon had stopped breathing.

The blue-grey colour of her skin was more consistent with oxygen deprivation.

At the time of her death, however, no one knew that a fast-acting paralytic drug might have prevented her from moving or breathing.

Scratches on David Davis

While at the hospital, Shannon’s mother noticed scratches on Davis’s face and hand.

The following day, Regina Davis also observed straight scratches on his face.

Davis claimed that tree branches had scratched him while he rode quickly through the woods seeking help.

On July 25, a funeral director observed the scratches and noticed that Davis appeared to have placed makeup over his face.

The scratches suggested that Shannon may have physically resisted him.

Because Shannon’s body was embalmed and some potential evidence was lost, investigators were never able to reconstruct every detail of a possible struggle.

The scratches nevertheless became part of the circumstantial case showing that Davis’s story was incomplete.

The Attempt to Arrange Cremation

At the hospital, Davis said that Shannon wanted to be cremated.

Her parents strongly objected.

As Catholics, they wanted their daughter returned to Toledo and buried according to their family’s religious traditions.

Richard Britton helped persuade Davis to permit Shannon’s parents to take custody of the body.

The decision proved essential.

Had Shannon been cremated immediately, investigators would have lost the opportunity to exhume her body, conduct further autopsies and discover the chemical evidence of succinylcholine.

Her body was temporarily taken to a funeral home in Hudson, Michigan, and later moved to Toledo.

During that process, Shannon’s clothing was removed and subsequently lost.

Her body was embalmed before a detailed forensic autopsy was conducted.

Embalming complicated the later toxicology but did not prevent investigators from eventually finding the evidence.

David Claims There Was No Insurance

Following Shannon’s death, Davis told relatives and friends that she had no life insurance.

Shannon’s father offered to help cover funeral expenses because he believed Davis lacked the money and insurance necessary to pay for the arrangements.

Soon afterward, Davis requested multiple copies of Shannon’s death certificate.

The requests alerted people close to the family that he might be preparing to file several insurance claims.

Shannon’s parents discovered that Davis was attempting to collect substantial benefits.

The amount was described in the appellate record as $220,000 from the two principal policies. Contemporary reports described total available coverage of approximately $330,000.

Davis reportedly received approximately $20,000 before further payments were stopped.

Robert and Lucille Mohr filed a federal interpleader action challenging Davis’s right to the remaining insurance money.

Davis failed to appear in that lawsuit.

The Funeral Reveals Another Lie

Members of Shannon’s family had been told that Davis’s parents died when he was young and that he had grown up without a family.

At Shannon’s funeral, a woman and man appeared who were identified as Davis’s mother and stepfather.

Their presence exposed another major lie.

Some relatives initially assumed that Davis might simply have been estranged from his family and found it easier to claim they were dead.

As investigators examined the rest of his history, it became clear that the orphan story was only one part of a much larger fictional identity.

The military service, university football career, deceased fiancée and other dramatic stories were either false or seriously distorted.

The Trip to Florida

Only days after Shannon’s death, Davis left Michigan with Jeanne Hohman.

On or around July 29, they began traveling toward Florida.

They stopped in Toledo, where Davis left Hohman at a shopping mall while he visited Shannon’s parents.

He returned pillows to the Mohrs and claimed that he intended to travel to a desert to think about his wife’s death.

He did not tell them that Hohman was waiting nearby or that she would accompany him to Florida.

Davis had not told Hohman that Shannon had been his real wife.

He did not tell her that Shannon had died or had been buried only days earlier.

According to Hohman, Davis did not behave like a man who had just lost someone close to him.

They spent approximately one week together in Florida before Hohman returned to Michigan.

This trip became powerful evidence that Davis’s marriage had been instrumental rather than emotional.

The woman he had told to wait for the conclusion of a secret mission was back at his side almost immediately after Shannon’s funeral.

The First Exhumation

Shannon’s parents refused to accept the horseback-riding story.

Their suspicions about the life insurance, Davis’s lies and his behaviour led to the first exhumation.

On August 25, 1980, doctors Steven and Renata Fazekas performed an autopsy on Shannon’s embalmed body.

The Mohrs specifically raised the possibility that their daughter had been killed.

The doctors therefore directed the toxicology laboratory at the Medical College of Ohio to conduct a broad search for drugs or foreign substances.

Tissue samples were stored for testing.

Thomas Carroll, a toxicologist at the laboratory, conducted a routine analysis using gas chromatography.

The instrument produced a significant unidentified peak.

Something unusual appeared to be present in Shannon’s tissue, but Carroll could not identify it.

Prepared samples were sent to other laboratories, including the Michigan State Police crime laboratory.

Those laboratories could not reproduce or identify the mysterious peak.

The first scientific effort had found something, but no one yet knew what it was.

The Investigation Reopens

The local investigation initially failed to produce sufficient evidence of homicide.

Shannon’s parents continued writing letters, contacting authorities and challenging the accidental-death explanation.

The Michigan Attorney General’s Office and Michigan State Police became involved.

Detective Sergeant Donald Brooks began examining the possibility that Shannon had been chemically immobilized before the supposed accident.

Brooks interviewed veterinarians who had worked at Davis’s farm.

One veterinarian suggested succinylcholine.

The suggestion was significant because the drug acts rapidly, paralyzes voluntary muscles and can stop a person from breathing while leaving the heart temporarily functioning.

Without mechanical ventilation, a lethal exposure can cause suffocation within minutes.

It was also the same substance Davis had previously discussed as a way to commit the “perfect crime.”

Succinylcholine and Anectine

Succinylcholine is a neuromuscular-blocking drug used in controlled medical settings to produce temporary paralysis.

One brand name is Anectine.

The substance interferes with communication between nerves and muscles. A conscious or partially conscious person may become unable to move or breathe independently.

The drug also presents a serious forensic difficulty.

It breaks down rapidly into substances naturally found in the human body. It is highly attracted to water and is not easily extracted from tissue using ordinary drug-testing procedures.

Davis had studied pharmacology and understood scientific and medical concepts.

Shannon’s cousin, Tori Abrams, testified that she visited the farm during the summer of 1980 and saw approximately ten or twelve syringes bundled together inside a refrigerator.

She also saw medication bottles marked Anectine in a freezer.

This testimony connected the theoretical murder weapon directly to Davis’s property.

Identifying the Unknown Chemical

When Detective Brooks proposed succinylcholine as the unidentified substance, Carroll and laboratory director Dr. Robert Forney were initially sceptical.

The drug was not expected to produce the chromatographic result found in Shannon’s tissue.

To rule it out, Carroll tested a known succinylcholine sample.

The result matched the unidentified peak.

Carroll and Forney repeated the comparison using five different gas-chromatograph columns. The results continued matching.

They then sought a more definitive analysis.

The scientists arranged to use specialized mass-spectrometry equipment at the Karolinska Institute in Stockholm, Sweden.

Because the drug was difficult to separate from biological tissue, they developed a preparation process using ion-pair extraction and chemical alteration.

They ran the tests with different controls to examine possible contamination or laboratory error.

Forney concluded that succinylcholine was present in Shannon’s body.

The Second Examination

Investigators needed more than a general indication that the drug was somewhere in Shannon’s tissue.

They wanted to determine where it had entered her body.

Another autopsy was performed.

The examination documented a puncture wound and several bruises, including bruising on Shannon’s right wrist and upper-right shoulder.

Samples from the suspicious areas were subjected to additional testing.

Forney detected high concentrations of succinylcholine around the bruises.

Pathologist Dr. Peter Goldblatt examined the upper-right shoulder and identified a cyst consistent with a subcutaneous injection.

The findings supported the conclusion that Shannon had been injected more than once or that Davis had attempted to inject the drug at multiple locations.

The head injury could not explain her death.

The toxicology and injection-site evidence could.

How Succinylcholine Killed Shannon

The prosecution’s medical evidence showed that succinylcholine blocked Shannon’s ability to use her voluntary muscles.

That included the muscles required for breathing.

Her heart could continue beating briefly while she remained unable to draw air into her lungs.

Death would occur through oxygen deprivation and respiratory failure.

Depending on the route of injection, the drug could begin acting within seconds or more gradually.

The bluish-grey appearance of Shannon’s skin when Britton reached her was consistent with severe oxygen loss.

The evidence also meant that Shannon may have remained conscious while becoming increasingly unable to move, speak or breathe.

The precise level of her awareness cannot be established from the surviving record.

What the medical evidence did establish was that she had not died from falling off her horse.

The Prosecution’s Reconstruction

Prosecutors argued that Davis arranged for the ride to occur without witnesses.

He excluded Shannon’s nephew, the dogs and the Brittons’ son.

Once alone in the woods, he stopped with Shannon and secured the horses to tree branches.

He then injected her with succinylcholine.

The evidence of more than one bruised injection area suggested that an initial attempt may not have delivered the drug effectively and that a later attempt succeeded.

As Shannon became paralysed and unable to breathe, Davis used the rock and surrounding scene to create the appearance of a riding accident.

The minor head injury and blood on the rock made the story plausible enough to avoid immediate suspicion.

Davis then returned to the Brittons’ house and performed the role of a panicked husband seeking help.

No living witness observed the injection.

The reconstruction was based on the toxicology, injection sites, scene evidence, Davis’s scratches, insurance motive and extensive evidence of premeditation.

The “Perfect Crime” Evidence

The conversation Davis had with Kay Kendall years earlier became particularly damaging.

He had discussed succinylcholine specifically and described its use in murder as nearly impossible to detect.

He had a background in pharmacology.

Anectine and syringes had reportedly been seen at his farm.

He bought life insurance almost immediately after marrying Shannon.

He told another woman that the marriage was part of a secret mission that would produce approximately $250,000.

He predicted that the assignment would end within weeks of Shannon’s death.

After Shannon died, he lied about the existence of the insurance and resumed travelling with the other woman.

Those facts formed a pattern that was difficult to explain as coincidence.

The Murder Indictment

On October 13, 1981, a one-person grand jury indicted Davis for first-degree murder.

By then, more than a year had passed since Shannon’s death.

Investigators had transformed what appeared to be a farm accident into a scientifically complex homicide case.

The indictment did not immediately bring Davis into custody.

He had sold the farm and was spending time aboard a sailboat with another girlfriend, Monica Yoezle.

The Disappearance From Haiti

On December 24, 1981, Davis contacted his Michigan attorney while he was on or near his boat in Haiti.

He told Monica Yoezle that he needed to return to Michigan to resolve legal issues involving alleged negligence in Shannon’s death.

Davis left Yoezle and the boat behind.

He instructed her to travel to Florida, obtain employment and wait for him to return.

She did not see him again until the murder trial years later.

Davis did not return to Michigan.

Instead, he disappeared.

The FBI joined the search at the request of Michigan authorities.

Years as a Fugitive

Davis remained missing throughout most of the 1980s.

Tips placed him in several warm coastal or island locations. Authorities investigated possible sightings in Florida, the Caribbean, Hawaii and elsewhere.

His sailing experience, false identities and comfort with travel allowed him to avoid detection.

The last confirmed sighting reported by authorities before his capture had been in Port-au-Prince, Haiti, on December 24, 1981.

While Shannon’s parents waited, Davis created another life.

He used the identity David Meyer Bell and eventually settled in American Samoa.

He worked as a pilot and entered another relationship or marriage without revealing that he was a fugitive accused of killing his previous wife.

Television Brings the Case Back to the Public

Michigan State Police worked with the television program Unsolved Mysteries to publicize the case.

An episode concerning Shannon’s death and Davis’s disappearance first aired in 1987.

The first broadcast did not immediately locate him.

The program was later repeated in December 1988.

After the repeat broadcast, a viewer provided information connecting Davis to American Samoa.

The tip gave investigators what they had lacked for nearly eight years: a current location.

Arrest in American Samoa

On January 6, 1989, federal and local authorities arrested Davis in American Samoa.

He was taken into custody without a violent confrontation.

At the time, Davis was 44 or 45 years old and had reportedly been living on the island for several years.

The arrest ended an international search that had begun after his 1981 indictment.

Davis was returned to Michigan under federal supervision.

On February 2, 1989, he appeared in Hillsdale County and was arraigned on the first-degree murder charge.

The judge ordered him held without bond.

Preparing for Trial

The prosecution faced an unusual evidentiary challenge.

No syringe had been recovered.

Shannon’s clothing and shoes had disappeared.

Some crime-scene and autopsy photographs could not be located.

Her body had been embalmed before the critical toxicology investigation began.

Potential evidence from beneath her fingernails had been lost during preparation for burial.

The toxicology method was complex and had been developed specifically to detect a substance believed to break down rapidly in biological tissue.

The defence therefore focused heavily on attacking the scientific reliability of the succinylcholine findings.

The prosecution relied not only on the laboratory evidence but also on Davis’s own statements, his romantic deception, insurance arrangements, conduct before the ride and actions after Shannon’s death.

The Scientific Challenge

Before trial, Davis’s lawyers asked the court to exclude the succinylcholine evidence.

They argued that the procedure used to identify the drug in embalmed tissue was novel, insufficiently validated and not generally accepted by the relevant scientific community.

The trial court held a hearing on the scientific evidence and allowed it to be presented.

Experts testified that gas chromatography, mass spectrometry, ion-pair extraction and the other basic laboratory procedures were recognized methods within analytical chemistry.

Although applying the techniques to embalmed tissue in a succinylcholine case was unusual, the underlying procedures were accepted and reproducible.

The defence presented experts and criticism challenging Forney’s conclusions.

The dispute gave jurors the responsibility of evaluating whether the chemical identification was reliable.

The Trial Begins

Davis’s murder trial began in Hillsdale County on November 28, 1989.

The prosecution presented a case involving premeditation, financial motive, false identities and forensic toxicology.

Witnesses described the rapid courtship and life insurance purchases.

Kay Kendall testified about Davis discussing succinylcholine as the perfect murder weapon.

Jeanne Hohman described his false government assignment and prediction that it would end shortly before Shannon died.

Witnesses from the farm and hospital described the riding trip, Shannon’s condition, the unusual scene and Davis’s scratches.

Tori Abrams described seeing syringes and bottles labelled Anectine at the farm.

Toxicologists and pathologists explained how they detected the drug and located the injection sites.

The Defence Case

Davis maintained that Shannon’s death had been a tragic accident.

His lawyers challenged the prosecution’s ability to prove that succinylcholine had actually been present in the body.

They emphasized that other laboratories initially could not reproduce the unidentified chromatographic peak.

They questioned whether contamination, embalming chemicals or mistakes in laboratory preparation could have produced a false result.

The defence also criticized the loss of Shannon’s clothing, shoes, photographs and possible fingernail evidence.

Without those items, the defence argued, it was impossible to conduct a fully independent reconstruction of the scene.

Davis did not testify on his own behalf.

Why the Circumstantial Evidence Mattered

Even without the toxicology, Davis faced a powerful collection of circumstances.

He had asked whether single women would attend the wedding where he met Shannon.

He proposed and married her with extraordinary speed.

He purchased large insurance policies immediately afterward.

He continued deceiving another woman and told her the marriage was part of a dangerous assignment.

He predicted that the assignment would soon end and would earn him approximately the same amount as the insurance.

He excluded usual companions from the final horseback ride.

Physical evidence suggested the horses had been tied.

Shannon’s injuries did not support a fatal fall.

Davis had scratches on his face and attempted to cover them with makeup.

He falsely denied that insurance existed.

He tried to have Shannon cremated.

He travelled with Hohman only days after the funeral and concealed Shannon’s existence and death from her.

Then he disappeared after being indicted.

Each fact could be debated individually.

Together, they supported the prosecution’s argument that Shannon had been selected, insured and deliberately killed.

The Verdict

On December 5, 1989, the jury found David Richard Davis guilty of first-degree murder.

The jurors deliberated for only a few hours before returning the verdict.

The decision established that Shannon had not died accidentally.

It also established that Davis’s conduct was premeditated rather than an impulsive act.

The jury accepted the prosecution’s conclusion that he used succinylcholine and staged the horseback-riding scene to obtain insurance money.

The Sentence

First-degree murder in Michigan carried a mandatory sentence of life imprisonment without the possibility of parole.

Davis received that sentence in January 1990.

The court viewed the murder as especially calculated.

Davis had exploited Shannon’s desire for love and marriage, arranged financial benefits around her death and used specialized knowledge in an attempt to conceal the cause.

He did not receive the insurance fortune he expected.

The Mohrs’ civil action and the criminal investigation prevented him from collecting most of the policies. Contemporary reporting indicated that he obtained approximately $20,000 before the payments were stopped.

Davis’s Appeal

Davis appealed his conviction to the Michigan Court of Appeals.

He argued that the succinylcholine evidence should not have been admitted because the testing process was scientifically unreliable.

He also complained that the prosecution had failed to produce photographs, Shannon’s clothing and shoes and evidence that might have existed beneath her fingernails.

The appellate court rejected his arguments.

It found that the scientific procedures used by Forney and Carroll were recognized analytical methods and that expert testimony supported their reliability.

The court also concluded that prosecutors had not deliberately suppressed the missing evidence. The materials were unavailable because they had been lost, returned to Davis or destroyed during the ordinary handling and burial of Shannon’s body before the case became a confirmed homicide investigation.

The conviction and life sentence remained in place.

Continuing Controversy Over the Toxicology

The succinylcholine testing continued to attract scientific criticism after the trial.

Some experts questioned whether the drug could reliably be identified in embalmed tissue after the passage of time.

Davis used those disputes in later efforts to challenge his conviction and continued claiming that Shannon had fallen from her horse.

The Michigan Court of Appeals noted that the defence had been able to cross-examine the prosecution’s experts and introduce criticism during the trial.

Later criticism was largely cumulative and would not probably have changed the jury’s decision, particularly given the extensive circumstantial evidence of planning and motive.

The conviction was therefore not dependent on an unquestioned belief that every scientist agreed with Forney.

The jurors heard the scientific dispute and still found Davis guilty beyond a reasonable doubt.

The Role of Shannon’s Parents

Robert and Lucille Mohr were central to the eventual prosecution.

They rejected Davis’s attempt to cremate Shannon.

They brought her home for burial.

They noticed the scratches on his face and questioned his false statement about insurance.

They filed the civil action that stopped most of the insurance payments.

They demanded the exhumation and broader toxicological testing.

When the initial investigation lost momentum, they continued writing letters and asking state authorities to review the case.

Their persistence preserved Shannon’s body long enough for specialists to identify the injection sites and develop the testing method.

Without their intervention, the death might have remained classified as an accident.

David Davis’s Death

Davis remained imprisoned for almost 25 years following his conviction.

He continued maintaining his innocence and unsuccessfully challenged the scientific evidence used at trial.

On November 9, 2014, he died at the Duane L. Waters Health Center, a Michigan Department of Corrections medical facility in Jackson.

He was 70 years old.

His life sentence ensured that he never returned to the freedom he had created under false identities in the Caribbean and South Pacific.

What Was Proven in Court

The jury found beyond a reasonable doubt that David Davis intentionally and with premeditation murdered Shannon Mohr.

The prosecution proved that Shannon’s head injury did not cause her death.

Experts identified succinylcholine in her tissue and found high concentrations at bruised injection sites.

Witnesses connected Anectine and syringes to Davis’s farm.

Davis had discussed the same drug as an ideal murder weapon before meeting Shannon.

He purchased substantial insurance coverage immediately after marrying her.

He created a false explanation for the marriage while maintaining a relationship with another woman.

He arranged for the final horse ride to occur without the people and animals who usually accompanied the couple.

He lied about insurance, attempted to arrange cremation, resumed his other relationship after the funeral and fled after being indicted.

The conviction was upheld on appeal.

Details That Remain Uncertain

No one witnessed Davis inject Shannon.

The syringe used in the murder was never recovered.

The exact sequence of the physical struggle in the woods cannot be reconstructed completely.

It is unclear whether Davis injected Shannon once or more than once.

The prosecution believed the bruises represented injection attempts, but the precise timing of each wound was not observed.

It is not known exactly how Davis caused Shannon’s head to strike the rock.

The surviving legal record does not prove that he persuaded her to have sex immediately before the murder, although the position of her clothing and shoes may have contributed to that theory.

The degree to which Shannon remained conscious after the successful injection cannot be known.

These uncertainties concern the mechanics of the murder, not the legal finding that Davis killed her.

Shannon’s Life Beyond the Case

Shannon is often remembered through the unusual poison used to kill her, the eight-year fugitive search and the forensic controversy at Davis’s trial.

Her family remembered something different.

She was a daughter, sister, aunt, nurse and friend.

She had selected a career dedicated to caring for sick and vulnerable people.

She wanted a marriage and children of her own.

Davis recognized that desire and used it to gain her trust.

The rapid romance was not merely an unfortunate relationship that later deteriorated.

The evidence showed that Davis entered the marriage with hidden relationships, false identities, financial plans and knowledge of a method he believed could conceal murder.

Shannon did not die because she was careless with a horse.

She died because a man transformed her hope for love into an opportunity for financial gain.

Conclusion

Shannon Mohr met David Davis at a wedding on August 4, 1979.

He appeared to be everything she had been waiting for: confident, successful, adventurous and ready to marry.

Seven weeks later, they exchanged vows in Las Vegas.

Eight days after the wedding, major life insurance policies were placed into effect.

Behind Shannon’s back, Davis continued deceiving Jeanne Hohman.

He told Hohman that the marriage was part of a secret government assignment and that the mission would end within approximately one year.

He claimed the assignment would earn him roughly $250,000.

In June 1980, he said only three or four weeks remained.

On July 23, Shannon and Davis took their horses to the Brittons’ farm.

Davis refused to allow Shannon’s nephew, the dogs or the Brittons’ son to accompany them back through the woods.

Twenty-five minutes later, he returned alone, sweating and carrying blood on his shirt.

Shannon was found on the ground with her shoes removed, her blouse open and her skin turning blue-grey.

Davis said her horse had thrown her against a rock.

At the hospital, he attempted to arrange for her cremation.

Her parents refused.

That refusal preserved the evidence that ultimately exposed the murder.

Davis claimed there was no life insurance, but he soon began requesting death certificates and seeking payments worth hundreds of thousands of dollars.

Shannon’s parents went to court to block the money and demanded a deeper investigation.

Her first exhumation produced tissue samples containing an unidentified chemical signal.

Investigators considered whether she had been chemically paralysed.

A veterinarian suggested succinylcholine.

The suggestion connected the case to Davis’s earlier statement that the drug could create the perfect murder.

Toxicologists compared the substance with the unknown result and found a match.

Using specialized analysis in the United States and Sweden, they identified succinylcholine in Shannon’s preserved tissue.

A second examination located bruised injection areas on her wrist and shoulder.

High concentrations of the drug were found around those sites.

The head injury was not fatal.

The drug had paralysed Shannon’s respiratory muscles and caused her to suffocate.

In October 1981, Davis was indicted for first-degree murder.

He disappeared two months later, leaving his girlfriend and sailboat in Haiti.

For almost eight years, he lived under another identity while Shannon’s parents waited for justice.

A repeat broadcast of Unsolved Mysteries generated the tip that led authorities to American Samoa.

Davis was arrested on January 6, 1989, and returned to Michigan.

At trial, prosecutors combined the scientific evidence with the history of deception.

Davis had discussed succinylcholine before meeting Shannon.

He had described it as a nearly perfect murder weapon.

He married Shannon rapidly, insured her, maintained another relationship and predicted that his supposed mission would end shortly before she died.

He controlled who accompanied them on the final ride.

He lied about the insurance, attempted to arrange cremation and resumed travelling with another woman days after the funeral.

On December 5, 1989, a jury convicted him of first-degree murder.

He was sentenced to life without parole.

The scientific testing remained controversial, but the Michigan Court of Appeals concluded that the methods were admissible and that Davis received a fair opportunity to challenge them.

He remained incarcerated until his death in 2014.

Shannon’s murder is frequently described as a triumph of forensic toxicology.

It was also a triumph of persistence.

Laboratory technology could examine only the evidence that still existed.

That evidence survived because Robert and Lucille Mohr refused to permit the cremation, refused to accept a convenient accident story and refused to stop asking why their daughter had died.

David Davis believed succinylcholine would disappear before anyone understood what he had done.

He was almost correct.

What defeated him was the combination of scientific curiosity, careful witness testimony and two parents who would not allow their daughter’s death to be forgotten.