Eyewitnesses are an essential part of criminal investigations. Due to the fact this case is decades old, this research avoided as much as possible any modern testimony. It is well known that human memory is highly unreliable especially across four decades. Any information from that time gathered from living sources and presented here is used anecdotally.
In contrast, written testimony from the time of the event was taken as fact, unless additional information proved otherwise. While any eyewitness from any time can be either accurate or completely wrong, the FBI files were the only starting point for a case this old. Reviews of the transcribed statements from the pilots and flight attendants all overlapped in their descriptions of Cooper and on the time line of events. Multiple independent people listening in on the radio communication between the hijacked plane and ground, all noted events and times that were in step and provided what is believed to be a very accurate description of the hijacking communications.The "302" files in the FBI archive are several inches thick and hold an impressive amount of work on the part of the FBI investigators. Although the Cooper Research Team had access to these files, only parts of them have been released to the public. Due to the nature of information in the 302's, the FBI has asked that they not be published in their entirety. Excerpts from the files are quoted where required for references. Some references to the 302's will have to be accepted as factual without reprinted proof.