Relatives say the father came to his 4-year-old daughter's rescue when the deadly confrontation unfolded.
Christopher Middleton, a 26-year-old Maywood father, is remembered as his loved ones scrawl messages, expressing their love and sorrow now that he's dead.
"Chris was a great father," said Middleton's cousin, Mathis Hoskin. "He was always helpful, never mad - always happy with a smile on his face."
He was the father of 4-year-old Taniyah Middleton. Saturday night, Maywood police say the girl darted into the street as an off-duty Chicago Police officer, on his way home, was riding his motorcycle on First Avenue.
Authorities say the officer ditched his bike, trying to avoid the girl, but the motorcycle clipped her anyway.
The Middleton family says the girl was crossing the street with an 18-year-old cousin to join her parents at a nearby restaurant.
"Her face was skinned, skin on her face," said Middleton's uncle, Darrell Davis. "She's in a lot of pain right now."
Once the girl was injured, relatives say her father and an 18-year-old relative went to help.
"Of course a father would be upset at the initial reaction of seeing the child in this condition and he confronted the guy and they got into a confrontation," Davis said.
Maywood police say the men attacked the 43-year-old police officer, an 8-year veteran on the force.
Authorities say he identified himself as a police officer before firing the deadly shot, but that's in dispute.
"He never let anyone know he was a police officer until after he shot him," said witness Cordell Haggard.
Middleton was transported to Loyola University Medical Center, where he was pronounced dead less than a half hour later. His family wants the officer to be held responsible for the shooting.
"We just want justice to be served," said Middleton's cousin Naomi Hoskin.
Along with Maywood Police, Chicago's Independent Police Review Authority is also investigating.
The girl and police officer both remain in the hospital on Sunday night.