A fiber line left the official server room and continued toward the basement corridor. On the department's approved network diagram, the line ended before reaching any listed device.
Maya asked, "Where does it physically go?"
Lena looked toward the hallway. "I don't know."
Maya picked up the preservation folder. "Then we stop reading diagrams and follow the cable."
Maya followed Lena and one of the FBI technicians down the basement stairs, while Chief Mercer and Rebecca came behind them. The utility corridor was narrower than the rest of the station and lined with electrical panels, network conduits, and maintenance access doors.
The technician used a handheld fiber tracer on the cable identified upstairs. "It continues past the official server room," he said.
Lena checked the building plan on her tablet. "There's no listed network equipment beyond this point."
Mercer looked along the corridor. "This section has electrical and environmental systems. There may be older infrastructure that never made it onto the current drawing."
"Then we document that first," Maya said.
They moved slowly along the wall until the tracer indicated the fiber was turning behind a large utility panel. The technician examined the screws. "These have been removed recently."
Rebecca stepped closer. "How can you tell?"
"The paint around the heads is worn, and the panel has fresh tool marks."
Mercer said, "Maintenance opens these panels all the time."
Lena shook her head. "Not this one. Facilities handles electrical access here."
Maya called the city facilities supervisor who had assisted at the storage annex. Frank Holloway arrived several minutes later, carrying a ring of keys and a maintenance log. He looked at the panel. "I don't recognize this as one of ours."
Mercer frowned. "It's inside a city building."
"That doesn't mean facilities installed it."
Maya asked, "Do you have any record of work behind this wall?"
Frank checked his log, then the building plan. "No."
Maya turned to the federal technician: "Photograph it before opening."
The panel was documented from several angles. Frank then removed the screws under federal observation. Behind it was a narrow access space with a fiber line and a power conduit running toward a reinforced door set farther into the wall.
Lena stared at it. "That room isn't on the plan."
Rebecca said, "There used to be mechanical storage down here."
Frank looked at her. "Not behind this wall."
Maya asked him, "Do you have a key?"
"No."
The federal technician examined the access hardware beside the door. "It's electronic."