The pattern in these investigations is consistent: a candidate is identified with a set of characteristics that are consistent with Cooper’s profile, but no direct evidence places them on Flight 305, and physical description comparison yields either ambiguous matches or clear discrepancies.
The FBI’s standard response when asked about specific named suspects has been consistent for decades: the bureau does not comment on specific suspects who have not been charged, and any identification claim should be evaluated against the evidence rather than accepted at face value.
This posture has frustrated some private researchers, who have interpreted the FBI’s silence on specific suspects as either endorsement or evasion. It is neither. The FBI is not commenting because it has no evidence sufficient to charge anyone, and naming suspects in a federal investigation carries legal consequences that require an evidentiary basis that does not exist for any named Cooper candidate.
—
## The Open File
The Cooper case file at the FBI is enormous, and portions of it are public. The 66 volumes represent roughly forty years of active investigation, conducted by the Seattle field office with contributions from other bureaus and from federal prosecutors. The file contains the kinds of material you would expect: witness statements, suspect files, laboratory reports, inter-agency communications, grand jury materials, tips and leads from the public, and analyses prepared by FBI analysts.
The public release of portions of this file under the Freedom of Information Act has allowed independent researchers to trace the investigation’s history in ways that were not possible while the file was fully restricted. Researchers have been able to identify which suspects received the most sustained attention, which laboratory analyses were conducted and when, and what the FBI’s own evolving theories about Cooper’s identity were at various points.