Dr. Papcun's Report on the Rodney King trial appears in the book "Letters of the Century"
(Read the letter)
by Grunwald and Adler
"Your appearance as the final witness in the Rodney King trial was decisive as to the outcome."---Milton Grimes, Esq.

"Dr. Papcun is a star!"---Attorney subsequent to Dr. Papcun's deposition, following which the opposition declined to proceed

"Please send your bill in before you find out how delighted the client is." --Attorney following a directed verdict subsequent to Dr. Papcun's testimony
From: America 1900-1999: Letters of the Century, Edited by Lisa Grunwald and Stephen J. Adler, pages 630-631:

In March of 1991, a twenty-five-year-old black motorist named Rodney King was brutally beaten, clubbed and kicked by four white Los Angeles police officers who later claimed that King had resisted arrest. The incident, which happened to be captured by an onlooker on videotape, crystallized a feeling among many citizens that police, especially in Los Angeles, were racist and corrupt, and that race relations hadn't improved much since the tumultuous sixties. Nightly news programs all over the country aired the images relentlessly. Two months later a local TV station became interested in the sounds on the tape as well and solicited the assistance of an expert. In 1992, an all-white jury would acquit the officers, setting off a series of riots in Los Angeles that would last three days and be responsible for fifty-one deaths.

Dear Mr. Kaye:
I have received from you via Federal Express a video cassette tape recording labeled "M/C P8 SPCL 'Rodney King' 4-24-91" followed by what appear to be the initials "K.S." In accordance with your request, I have enhanced the acoustic part of the recording by attenuating ambient noise (which appears to be the noise of a helicopter) that interferes with the intelligibility of the recording, and attempted to discern what was being said in the recording. I have listened to the recording with appropriate equipment that transduces the full range of audio frequencies relevant to understanding the speech in this recording. I have also listened to the recording under various conditions of parametric filtering. Consequently, I can report to you the following words shouted by men in the distance:

12:53:04 Voice 1: "Nigger, hands behind your back!"

12:53:09 Voice 2: "Hands behind your back!"

12:53:13 (Voice 2): "Behind your back!"

I am prepared to explain in detail the technical characteristics of the playback and filtering methods I used, and to testify under oath as to the conclusions I have reached. Enclosed you will find a copy of the video cassette recording with the sound track enhanced under three of the filtering conditions I used in my assessment of the recording. I make the representations contained in this letter solely as a private citizen, and not as a representative of the United States Government or the University of California. Under separate cover I will send a curriculum vitae listing my technical qualifications in this area of expertise. Please do not hesitate to contact me if I can answer any questions or furnish any additional information.

Sincerely yours,
George Papcun, Ph.D.

Post Script: In the trial at which Rodney King successfully sued the City of Los Angeles for damages, I played the enhanced recording to the jury. I was the final witness.