Antonacci's father, Al Antonacci, believes his son's death could have been prevented.
"If they had just taken him off base," he said, "I believe my son would be alive today."
A spokesman for the Naval Criminal Investigative Service would not comment on Antonacci's death or the alleged threats against him because its investigation is ongoing.
But from the beginning, the Antonaccis feel they have been misled. They say the Navy spokesman who came to their Long Island home to deliver grim news of their son's death initially said he had died in a car crash.
"It was a misdirection from the start," said Antonacci's father. "First, it was a car accident, then a massive aneurysm in his bunk."
Kyle's sister, Karissa Antonacci, finally contacted her brother's Navy colleagues via Facebook.
Said Antonacci's mother, "My daughter called me and said 'Do you want me to tell you how he died, or do you want the Navy to tell you?' She found out online."
Antonacci's family say they went on to learn even more disturbing information. According to the coroner's report, Antonacci suffered hemorrhaging around his face, a broken nose and other injuries the medical examiner said were "not consistent with a typical hanging."
The medical examiner wrote, "I was not 100 percent convinced this was a self-inflicted hanging."
Antonacci's parents were startled when they saw their son's body.
"He looked like he was tortured," said Lisa Antonacci, Kyle Antonacci's mother. "He had a giant black eye and scratches on his hands."
The Antonaccis say the were also told by the coroner's office that more than 100 photographs taken in the course of the autopsy had somehow vanished because of "technical problems." The coroner's report mentions that photographs were lost.
Six months after they buried their son, the Antonaccis paid tens of thousands of dollars to have his body exhumed. They hired famed medical examiner Dr. Michael Baden to conduct a second autopsy. Baden's autopsy discovered that -- Antonacci's hyoid bone, the only bone in the throat, which could provide crucial information as to how he died -- is missing.
Baden's report was inconclusive, in part because of the missing photographs and hyoid bone.
"We were desperate to know what happened to our son, and we have no answers," Antonacci's mother said.
Antonacci's mother says she isn't sure if her son was murdered or if all of the pressure and threats caused him to take his own life.
"I think he was either killed or bullied to death," she said. "The Navy didn't help him or protect him. He would have been safer in Iraq than he was in Illinois."