>In 1977, six top FBI officials scheduled to appear before the United States House Select Committee on Assassinations died.
William C. Sullivan, Ex‐F .B .I. Aide, 65, Is Killed in a Hunting Accident
Nov. 10, 1977
William C. Sullivan, former head of the Federal Bureau of Investigation's intelligence operations who broke in dramatic fashion with the late J. Edgar Hoover, was killed early yesterday in a shooting accident near his home in Sugar Hill, N.H. He was 65 years old.
Maj. Mason J. Butterfield, law enforcement director of the New Hampshire Fish and Game Department, said that Mr. Sullivan, who had been on the way to meet two hunting companions shortly after daybreak, had been shot and instantly killed by another hunter, Robert Daniels Jr., 22, who had mistaken Mr. Sullivan for a deer.
https://www.nytimes.com/1977/11/10/archives/william-c-sullivan-exfbi-aide-65-is-killed-in-a-hunting-accident.html
Examining NH's Own JFK Assassination Mystery
Investigating Bill Sullivan's role in JFK's death
Bill Sullivan was too controversial to die quietly. As the number three man in the FBI during the turbulent mid-20th century, he collected the nation’s secrets, and when he retired to Sugar Hill, New Hampshire, they came with him. And in November of 1977, they died with him at the hands of young hunter who mistook him for a deer. His untimely death came just weeks before he was to testify before a Congressional inquiry into the assassination of John F. Kennedy, an investigation that he led.
https://www.nhmagazine.com/examining-nhs-own-jfk-assassination-mystery/