Lt. Joe Gliniewicz served as a police officer for more than three decades and lived in Fox Lake, Illinois, a suburb about 55 miles north of Chicago.
"Not only did Fox Lake lose a family member, I lost a very dear friend," the town's mayor Donny Schmit said at a news conference Tuesday.
Gliniewicz was a 30-year, decorated veteran of the force, Schmit said.
Gliniewicz, 52, was also a married father of four boys and an active member in the community, reportedly spending some of his time off the clock as a youth volunteer.
"Many residents in here knew him as G.I. Joe, we remember him as someone deeply committed to Fox Lake, to the profession and his fellow officers," Schmit said.
Gliniewicz was found shot by a back-up officer after he radioed in that he was going to pursue three suspicious individuals on foot. The only descriptions Gliniewicz gave of the men was that two of the men were white and one was black.