Bernard Hightower was charged with felony aggravated battery, causing great bodily harm, according to CPD.
He was arrested about 2:09 a.m. Thursday in the 100-block of Madison Street in Oak Park, police said.
He's accused of battering a woman on a Blue Line train near Oak Park. One witness said the attack left her face bloodied and badly swollen.
There was reportedly commotion on the conductor's radio, then an announcement the train was going to stop at Oak Park, after a man viciously attacked a woman, the witness, who identified himself as Mike, said.
"It's absolutely terrible. I don't really know what happened and what really caused that, but I feel very sorry for her," Mike said. "I don't think, I don't think that should ever happen to anybody regardless of the case scenario. And it was just a very terrible scene I kind of wish I didn't see it."
The conductor stopped, and asked all riders to get off the train and call police.
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Oak Park police responded to the scene, and the woman was reportedly taken to Loyola Hospital with serious injuries.
The extent of the woman's injuries was not immediately clear later Saturday morning.
The incident took place on the train, but moved onto the Oak Park platform after someone pressed the assistance button near the Austin Boulevard stop, according to police.
A witness told police the incident began with an argument near Kedzie Avenue.
Hightower is next due in court Saturday.
The video in the player above is from an earlier report.