The 29-year-old Oliver was found dead Tuesday night in Marietta, about 20 miles northwest of Atlanta, Cobb County Medical Examiner's investigator Tim Weaver said.
Oliver died of a self-inflicted gunshot wound, Cobb County police Sgt. Dana Pierce said.
Oliver was a 2007 fourth-round supplemental draft pick from Georgia after he was ruled academically ineligible his senior year. He played four seasons with the Chargers; his best year was 2010, when he started eight games and had 62 tackles along with an interception.
Oliver moved to the New Orleans Saints in 2011 but was released after training camp. He returned to San Diego for one more season.
"It's sad to lose anyone, for that matter, but a guy that you played with - I can remember interactions with him like it was yesterday," Chargers quarterback Philip Rivers said.
Tight end Antonio Gates remembered Oliver as an easygoing teammate who kept mostly to himself.
"You just never know; life is so short," Gates said. "My condolences and prayers go out to his family and kids."
Oliver, a native of suburban Atlanta, also was remembered for his career at Georgia, where he played from 2004-06. He started all 13 games his final season and finished with seven interceptions and five forced fumbles in his college career.
One of Oliver's best games at Georgia was holding Detroit Lions star Calvin Johnson, then at Georgia Tech, to just two catches for 13 yards in 2006. The defensive back had an interception in the game's final minute to preserve a 15-12 victory over the Yellow Jackets.
"It's heartbreaking for me personally, for our staff, for the Bulldog Nation I'm sure, and obviously for his family," Georgia coach Mark Richt said. "I was crushed this morning when I heard it, quite frankly. I really haven't been able to keep it off my mind to be honest with you. We've got to find a way to reach out and help in any way we can. If there's some way that the Bulldog Nation can rally around that family, I hope everybody would be encouraged to do so."
The university said Oliver was survived his wife, Chelsea, and two children. Funeral arrangements had not been finalized.