Though his body has been laid to rest, the story of how Illinois cop Lt. Charles Joseph Gliniewicz died earlier this month, has developed into a crime mystery.

It started as a story of a beloved police officer slain in the line of duty shortly before he was due to retire. The incident captured national attention and gripped the town of Fox Lake, where more than 400 officers and federal agents, K-9 units, and helicopters, launched a manhunt for three suspects.

But on Tuesday, local media reported that investigators had started looking into suicide as a possible cause of death. This was several days after local coroner Thomas Rudd said that the fatal gunshot wound was to the torso, not the back or neck, as had previously been reported, raising the possibility that Lt. Gliniewicz may have killed himself.

“Right now, all unnatural deaths are up for suggestion. That means homicide, suicide, accident, undetermined,” Dr. Rudd told the Chicago Tribune, angering investigators – who said he had compromised the investigation – and the officer’s family.

"My father never once had a single suicidal thought in his life," Donald Gliniewicz, son of Lt. Gliniewicz, told the Chicago Daily Herald.

Lt. Gliniewicz, a 30-year police veteran called “G.I. Joe,” by his friends, died on Sept. 1 after telling a dispatcher that he was pursuing three men.

By the time backup officers arrived in the remote, marshy area, the officer was dead, lying face down, a .40-caliber service weapon lay nearby, the Tribune reported.

Hundreds of residents held a vigil to honor him, lining the small town’s main street holding flags and homemade signs praising the officer for giving his life to protect them, according the Washington Post.

“Even the criminals liked him," a long-time friend told a local NBC affiliate.

But in the ensuing weeks, no suspects have been found; no witnesses identified.

The fatal shot “struck him underneath his vest, fired in a downward trajectory, near the heart,” according to Fox News.

Detectives are waiting for the results of a number of scientific tests on evidence recovered from the area where Lt. Gliniewicz was shot.

This report includes material from Reuters and the Associated Press.