A Dictabelt recording from a motorcycle police officer's radio microphone stuck in the open position became a key piece of evidence cited by the House Select Committee on Assassinations (HSCA) in their conclusion that there was a conspiracy behind the assassination of John F. Kennedy on November 22, 1963. Made on a common Dictaphone-brand dictation machine that recorded sound in grooves pressed into a thin vinyl-plastic belt, the recording gained prominence among Kennedy assassination conspiracy theorists following the HSCA's 1978 conclusion, based in part on this evidence, that there was a "high probability" that Lee Harvey Oswald did not act alone and that the Kennedy assassination was the result of a conspiracy.
The recording was made from Dallas Police Radio Channel 1, which carried routine police radio traffic; Channel 2 was reserved for special events, such as the presidential motorcade. The open-microphone portion of the recording lasts 5.5 minutes, and begins at about 12:29 p.m. local time, a minute before the assassination.[1][2][3][4][5] Verbal time stamps were made periodically by the police radio dispatcher and can be heard on the recording.[6]
- ^ In addition, there are two earlier open-mic portions of the recording, one at 12:24 p.m. (4.5 seconds) and the other at 12:28 p.m. (17 seconds). J. C. Bowles, The Kennedy Assassination Tapes: A Rebuttal to the Acoustical Evidence Theory Archived 2008-08-29 at the Wayback Machine, 1979.
- ^ Warren Commission Hearings, Commission Exhibit 705, Radio log of channel 1 of the Dallas Police Department for November 22, 1963 Archived June 12, 2008, at the Wayback Machine, vol. 17, p. 395.
- ^ Barber, Steve. "The Acoustic Evidence: A Personal Memoir". mcadams.posc.mu.edu. John McAdams. Archived from the original on October 20, 2014. Retrieved July 20, 2014.
- ^ "Reexamination of Acoustic Evidence in the Kennedy Assassination," Committee on Ballistic Acoustics, National Research Council, SCIENCE, 8 October 1982, [1] Archived 2008-08-29 at the Wayback Machine
- ^ "Signal Processing Analysis of the Kennedy Assassination Tapes," R.C. Agarwal, R. L. Garwin, and B. L. Lewis, IBM T. J. Watson Research Center, [2] Archived 2008-11-21 at the Wayback Machine
- ^ Warren Commission Hearings, vol. XVII, pp. 390-455, CE 705, Transcription of all radio transmissions from Dallas police channel 1 and channel 2 from 12:20 p.m. to 6:00 p.m., Nov. 22, 1963 Archived 2007-09-27 at the Wayback Machine.