Joliet teenager convicted of shooting Grundy County Sheriffs Deputy

Demarcus Denwiddie was found guilty on all charges

GRUNDY COUNTY – A Joliet teenager was convicted Friday for the attempted murder of a Grundy County Sheriff’s Office deputy.

Demarcus Denwiddie, 19, of Joliet was found guilty by a jury on three counts of attempted murder, three counts of aggravated battery and aggravated discharge of a firearm.

Grundy County State’s Attorney Russell Baker said he was relieved at the outcome of the case.

“We had a really good case,” he said. “Tyler Post is such a good police officer, we knew they would never find any fault in anything he did, so it was just a matter of can you convince a jury that there was intent to kill and it was overwhelming that that could be proven. So it was kind of like proving the obvious.”

According to prosecutors, Post tried to stop Denwiddie’s vehicle, but the 19-year-old fled the scene after the deputy got out of his car. Denwiddie then crashed near the railroad crossing at Grand Ridge Road in Mazon, prosecutors said.

After the crash, Denwiddie fled his vehicle and Post chased after him. As Post was closing in, Denwiddie fired four rounds, shooting the officer in the arm, chest and back area, prosecutors said. Post was wearing a bulletproof vest, which stopped two of the three rounds fired at him.

In the process of firing the gun, Denwiddie also shot himself in the left arm. He was unable to fire any of the 13 rounds that were left in the magazine, as one round jammed in the chamber. Denwiddie was apprehended at an apartment complex on Depot Street in Mazon a few hours later.

During closing arguments, Baker and Assistant State’s Attorney Kyle Klukas outlined their case saying Dewinddie’s actions Oct. 7 to prove that he was willing to do anything, including kill to not be arrested by Post, and throughout the entire incident Denwiddie was thinking only about himself.

However, Klukas said Post’s actions prove he did the exact opposite. Every decision he made was in the interest of public safety.

Grundy County Public Defender Michael Olewinski said in his closing saying that Denwiddie was 18 at the time of the offense and he made “stupid decisions.” He implored the jury to think about what happened after the accident, citing that Denwiddie was not aiming for Post, but the red truck and he thought his life was in danger.

“All Demarcus has seen is all these civilians and he is running and he is scared,” Olewinski said.

Baker said Olewinski was using minimizing statements with phrases like “stupid decisions, bad decisions,” and Denwiddie made deadly decisions throughout the incident.

“This is not a stupid decision. This is an ambush and an execution,” Baker said. “He shot him as many times as he could.”

After the trial, Grundy County Sheriff Ken Briley said that the court proceedings went as to be expected and he believed the jury got it right.

“I think Tyler and his family are relieved,” he said. “I truly think that they probably feel like there are no winners in this situation, but that they are glad Tyler is here with us today – alive and well. Tyler is an amazing man. He has gone through something that most police officers never go through in their career, and he’s a five-year cop.”

Baker said Dewiddie faces a minimum of 45 years in prison. His next hearing is at 10:30 a.m. April 6 at the Grundy County County Courthouse in Morris.

Maribeth M. Wilson

Maribeth M. Wilson has been a reporter with Shaw Media for two years, one of those as news editor at the Morris Herald-News. She became a part of the NewsTribune staff in 2023.