Antonacci's family, however, doesn't believe he committed suicide and fear he
might have been murdered for his role in the investigation, according to ABC News.
The family says they were first told Antonacci had died in a car crash, then that he had an aneurysm; they learned the truth about his death on Facebook, they told ABC News.
The Antonaccis say their son was targeted by the Marine's friends and had asked the Navy to move him off base at Naval Station Great Lakes, Ill., for protection. They say his autopsy showed facial injuries inconsistent with a self-inflicted hanging.
Read more about the death of Kyle Antonacci