Oak Park police said Jerell Thomas has been charged with first-degree murder, attempted murder of a peace officer, possession of a stolen firearm and unlawful use of a weapon by a felon in connection with the shooting.
Police said investigators consider Thomas a "habitual criminal" with a previous history of multiple arrests for aggravated battery to a police officer, domestic battery, battery and resisting a police officer.
The charges come as Oak Park Police Department remains deep in mourning after 40-year-old Reddins was shot and killed Friday morning.
Reddins, a five-year veteran with the department, is the first Oak Park officer to die in the line of duty since 1938.
Oak Park police said Reddins was working a patrol beat when he responded to the 1000-block of Lake Street around 9:30 Friday for a report of a person seen leaving a Chase Bank in the area with a gun.
Police said Reddins and other officers asked Thomas to show his hands, and that is when he brandished a gun. Thomas then began to shoot, striking Reddins on the left side of his body.
Reddins was rushed to Loyola University Medical Center, where he died just after 10 a.m. Friday.
Police said Thomas was shot in the leg and was also taken to Loyola for treatment. He is stable and in custody.
No bond hearing has been set while Thomas is being treated at the hospital.
An emotional and extensive caravan of first responders could also be seen transferring Reddins to the Cook County Medical Examiner's Office on Friday.
Reddins was sworn in as an officer in May 2019 and was described as a "family man." He leaves behind a 19-year-old son.
Oak Park Police Chief Shatonya Johson says Reddins' loss is felt throughout the department.
"I'm hurting," Johnson said. "This is the worst day of any chief of police."
A black band already wrapped around her star, Johnson felt the weight of the line-of-duty loss that few Oak Park chiefs before her have known. She hired and then promoted Reddins over the last five years.
"I personally knew Allan, because I did his background investigation, and I quickly identified he had a talent that was needed here," Johnson said.
The Chicago Police Department released a statement following Reddins' death, writing, in part, "The Chicago Police Department extends our heartfelt condolences to the family, friends, and coworkers of Oak Park Police Department Detective Allan Reddins who was shot and killed in the line of duty today (Friday). We will continue to assist and support our neighboring department through this difficult time."
Anyone with information is asked to call Oak Park police at 708-386-3800.
Anonymous tips can be provided at 708-434-1636 or online at www.oak-park.us/crimetip.