
Internet Archive: Details: The Jonestown Death Tape (FBI No. Q 042):
"An audio recording made on November 18, 1978, at the Peoples Temple compound in Jonestown, Guyana immediately preceding and during the mass suicide or murder of over 900 members of the cult."
Devastating and surreal. This was apparently recorded over a audio palimpsest of pop songs, slowed down to a syrupy dirge, backward? Just saw the excellent documentary on PBS, "Jonestown: The Life and Death of Peoples Temple"
from the internet archive