Island Lake man accused of threatening to shoot people, pistol-whipping man in bar pleads guilty

A man accused of threatening to shoot people in an Island Lake bar pleaded guilty Tuesday to possessing a stolen firearm and aggravated battery in a public place.

Judge Tiffany Davis sentenced Thomas Garrison, 52, to 180 days in McHenry County jail and 30 months felony probation, but because he’s already served 348 days in jail since his arrest, the jail time is considered served, the judge said.

As part of his probation, Garrison is required to obtain an anger management and substance abuse evaluation within 45 days and follow any resulting recommendations, the judgment order filed in McHenry County court shows.

He also was ordered to have no contact with Maverick’s Brew Pub, where authorities said he threatened people who’d come to the aid of a woman who had rejected his “unwanted advances.”

Assistant State’s Attorney Garrett Miller said police responded to the bar around 1:30 a.m. May 16, 2025. Police said others in the bar defended the woman and removed Garrison from the bar. Miller said Garrison then threatened to “shoot their heads off,” and then was seen going back to his pickup truck and loading a shotgun.

As he returned to the bar — with what authorities said was later shown to be a defaced Maverick 88 12-gauge shotgun — a man tried to stop him. A fight ensued in which Garrison was accused of pistol-whipping the man, causing “deep lacerations to the back of his head.” The man was able to get the gun away from Garrison, unload it and hold it until police arrived, Miller said.

Garrison has past convictions making it illegal for him to own a firearm, authorities said.

Assistant Public Defender David Giesinger had said Miller’s claim that Garrison “was approaching the bar with the gun is a misstatement.” The attorney also said Garrison denied having a loaded gun and has said the fight with the other man was at the truck and he was trying to leave the bar.

With his plea, additional charges were dismissed Tuesday, including possessing a firearm with a defaced serial number, possessing a firearm while his Firearm Owner’s Identification card was revoked, additional counts of aggravated battery and disorderly conduct, court records show.

As part of his probation, Garrison also is not allowed to consume any illegal drugs or drink alcohol and is required to submit to random screenings, the judge said.