The memorial took place at the Thompson Center downtown, the same place Bauer was shot and killed last February while chasing a suspect.
RELATED: CPD commander fatally shot at Thompson Center in Loop
Bauer had intervened in a chase as Shomari Legghette, a 44-year-old four-time felon, ran from police officers downtown.
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The two men struggled outside the Thompson Center. Legghette allegedly pulled out a gun and shot Bauer six times. Legghette was caught as he ran from the stairwell. Police said he was wearing body armor and was carrying small amount of heroin and cocaine.
Police said Bauer never had the chance to fire his weapon. He died at the hospital later that day. The commander was a 31-year veteran of the force who led the 18th District. He was 53.
Legghette was initially charged with first-degree murder of a police officer, aggravated use of a weapon by a felon and drug possession. In March, a grand jury handed up new counts and he was formally indicted on 56 counts, including 24 counts of murder and 32 counts of armed violence and related weapons charges.
RELATED: Friends remember CPD Cmdr. Paul Bauer a year after his death
Tuesday, three of Bauer's childhood friends -- Steve Matteo, John Escalante and Dan Kiehn -- sat down with ABC7 to share memories of Bauer.
"He could give a one liner, a zinger, and then he would have a smirk and know you had no comeback," recalled John Escalante.
"He was never the center of attention but he always got in his two cents," said Dan Kiehn.
"He had a great laugh. He'd always slap his knee," Steve Matteo remembered.
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The three childhood friends, who called themselves Bauer's "brothers," attended the parish school of St. Clare of Montefalco -- now Talman Elementary.
Once, they even sneaked into the ceiling to sign their names on a beam. They remember the silly school days and the lasting friendships, as well as Bauer -- the kid who brought them together and kept them together over the years.
His lifelong friends reminisced in what had been their 5th grade classroom.
"It seems like we've known him my whole life," Matteo said. "He was a brother who was part of my family."
"He worried more about other people than he worried about himself, he really did," said Escalante. "He always wanted to make sure everything was okay with everybody else."
"He's always here, but I miss the guy that's not sitting here," said Kiehn.
"February 13th will never be just February 13th again," Escalante agreed.
"He wasn't just a policeman, he was a great friend and a son and a brother," Matteo said.
"He challenges me every day to be a better dad, a better husband. Just a better person in general," Kiehn said.
"It was a tragic thing that happened and, gosh, I miss him, but I'm just grateful to have known him," said Matteo.
Bauer did not actually have any brothers, but he is survived by three sisters.
ABC7 anchor Alan Krashesky recently sat down withBauer's three sisters, who shared their stories for the first time.
Watch Krashesky's exclusive interview at 10 p.m. Wednesday.