DeLoach died late Wednesday, The Island Packet in Hilton Head reported. He was 92. His son, Greg, Hilton Head's assistant town manager, said the death was from natural causes.
During his years as third in command at the FBI after Hoover and Clyde Tolson, DeLoach was involved in many significant investigations, including the search for the assassin of Martin Luther King Jr. He called President Lyndon Johnson in 1964 to tell him that the bodies of civil rights workers Mickey Schwerner, James Chaney and Andrew Goodman had been found in Mississippi.
DeLoach retired from the FBI in 1970. He later wrote "Hoover's FBI: The Inside Story by Hoover's Trusted Lieutenant," which was published in 1995.
DeLoach admitted having mixed feelings about the FBI, saying he retired when he did because Hoover appeared unable to let go of the directorship. Hoover died in 1972.
"I loved him, but I didn't like him," DeLoach once said.
DeLoach was a vice president at PepsiCo Inc. for 15 years after leaving the FBI. When he moved to Hilton Head, he also served as a Beaufort County commissioner.
He remained involved with law enforcement, helping local police officers get FBI training and aiding in a major cocaine investigation in the late 1980s.