Alexander Taylor was found guilty of aggravated battery of a victim over 60 and aggravated battery in a public place.
A Chicago police sergeant intervened in the incident back in September 2018.
He was off-duty in Chinatown when he said he happened to see then-45-year-old Taylor hit 91-year-old Yen Jit Wong as he walked down Wentworth Avenue near 24th Street.
Bazarek was taking a break from a retirement seminar at police headquarters nearby. While driving for a cup of coffee, he spotted a disturbed man on the sidewalk.
"He was ranting, wild, violent hand gestures, screaming at the sky, the sidewalk," Bazarek recalled. "As I thought that to myself, I saw this guy strike out at the elderly Asian male, knocking him right to the pavement."
Stuck in traffic, Bazarek, who has over 100 years of police service in his family, kept his eyes on Taylor and called for backup on his cellphone. Civilians on the street rushed to to help Wong.
"When I saw that I had help coming to back me, I cut him off, told him he was under arrest, get his hands in the air, he complied, still ranting," he recalled.
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Bazarek quickly arrested Taylor after witnessing the attack. Wong's family said they are grateful for what the sergeant did.
"He was off-duty and he was passing by. A lot of people just, you know, didn't care," said Eddie Lau, Wong's son-in-law.
Wong's relatives said he hit his head on the ground and had bleeding around his brain, as well as a broken collarbone. They said at the time of the attack, Wong was on his way home after having lunch with his son.
"My grandfather wasn't a threat to anybody in the community. He enjoyed taking walks in the community," Wong's grandson, Jeremi Yu, previously told ABC7 Chicago.
Wong was treated in intensive care at Northwestern Memorial Hospital. He was eventually moved out of the ICU, but he was still undergoing physical therapy and remained on a feeding tube.
Upon arrival at the Chicago police lockup, Taylor spat on a government official through the bars of his cell and then smeared feces on the door and walls of his cell. He was placed on a psychiatric hold at Mt. Sinai Hospital. Authorities said he has been held for psychiatric reasons in the past as well.
Taylor has a history of violence against others, with a class X attempted murder charge on his record and a 2006 conviction of aggravated battery, as well as a history of self-harming behavior.
He's due back in court March 28.
The video in the player above is from an earlier report.