Lieutenant Charles Joseph Gliniewicz made it look like he was killed in the line of duty, triggering a large manhunt, after stealing funds from a youth program

A northern Illinois police officer whose fatal shooting triggered a large manhunt in September carefully staged his death to make it look like he was killed in the line of duty, and had been stealing for years from a youth program he oversaw, authorities said Wednesday.

Lake County Major Crimes Task Force commander George Filenko, who led the two-month investigation into the 1 September death of Fox Lake police lieutenant Charles Joseph Gliniewicz, said the popular officer embezzled thousands of dollars from the Fox Lake Police Explorer program for seven years. He said Gliniewicz spent the money on things like mortgage payments, travel expenses, gym memberships and adult websites. Filenko said in total, the money pilfered by Gliniewicz was in the “five figures”.

“We have determined this staged suicide was the end result of extensive criminal acts that Gliniewicz had been committing – in fact he was under increasing levels of personal stress from scrutiny of his management of the Fox Lake Police Explorer program,” Filenko said at a news conference announcing the investigation’s findings.

“Gliniewicz committed the ultimate betrayal,” he added. “This is my first time as a law enforcement officer, in my career, that I felt ashamed by the acts of another police officer.”

Fox Lake village administrator Anne Marrin was one of the officials who first suspected the officer might have been involved in inappropriate behavior. “When I heard he was concerned that I was asking tough questions about the explorer program, it only confirmed to me that asking the tough questions was the absolute right thing to do,” said Marin, who was threatened personally by Gliniewicz before his death, according to investigation documents.

Facebook Twitter Pinterest Police on foot and in the air search for suspects in the shooting on 1 September 2015 in Fox Lake, Illinois. Photograph: Brian Hill/AP

On the day he died, Gliniewicz radioed in that he was chasing three suspicious men in a swampy area near Fox Lake, which is north of Chicago. Backup officers later found the army veteran’s body about 50 yards from his squad car.

Gliniewicz’s death set off a large manhunt, with hundreds of officers searching houses, cabins and even boats on area lakes. Helicopters with heat-sensing scanners and K-9 dog units scoured the area for days. Around 50 suburban Chicago police departments and sheriff’s offices assisted, racking up more than $300,000 in overtime and other costs, according to an analysis that the Daily Herald newspaper published in early October.

Authorities said in October that Gliniewicz, 52, was shot with his own weapon, and released only the vague description of three suspects that Gliniewicz had radioed in. They tracked down three men captured on a home security video system, but all were cleared and no one was ever arrested.

Gliniewicz took elaborate steps to try to make it look like he died in a struggle, including shooting himself twice in the torso through his ballistic vest. One bullet pierced the officer’s upper chest.

The officer’s death was cited by some as proof of a “war on police” in the midst of an ongoing national discussion about excessive force by police.

An outpouring of grief swept Fox Lake, a community of 10,000 residents located about 50 miles north of Chicago. Signs with the officer’s picture hung in storefront windows and flags flew at half-staff in honor of the 30-year police veteran. Many of the village’s utility polls had even been wrapped in blue ribbon, in honor of Gliniewicz.

The tattooed officer with a shaved head was described by those who knew him as tough when necessary, but also as sweet and a role model to youngsters aspiring to go into law enforcement.

More than 125 investigators stayed on the case for weeks, tallying about 25,000 investigation hours. Questions arose in mid-September, and investigators began to concede that they could not rule out suicide or an accident. Rumors of suicide swirled for weeks, including a bizarre incident where a former Chicago officer threatened investigators with death unless they ruled Gliniewicz’s death a suicide.

Investigators looked though 6,500 pages of Gliniewicz’s text messages and 40,000 personal emails before reaching a conclusion.

Gliniewicz’s family dismissed the suggestion of suicide. His son DJ Gliniewicz said his father “never once” thought of taking his own life, and described how his dad spoke excitedly about what he planned to do after retiring.

Gliniewicz had four children.

The Associated Press contributed to this report.