Ontario Billups' sisters, however, say there was no reason for their brother to be shot to death.
According to police, the female officer feared for her life when Billups moved towards her.
The Independent Police Review Authority is investigating the case.
The shooting happened Saturday night in the 8100-block of South Ashland Avenue, an area Chicago police say is known for drug sales and gang activity.
Authorities had not confirmed Sunday whether drugs were found in Ontario Billups' possession, but the man's family was speaking out against who they call a trigger-happy police officer.
Billups leaves behind 16 siblings. One is a former military police officer who was scheduled to take the Chicago Police Department's entrance exam next week. Now, she says she is not so sure she will do so.
"He had some problems back in 2001, but on December 4th, he was an unarmed individual who was shot by a police officer," sister Angela Billups said.
Billups' family acknowledged Sunday that their brother was no angel. He was convicted of attempted murder several years ago and was convicted of felony drug possession earlier this year. The say he was a man with a record. However, they say, the police officer who shot him Saturday was wrong.
"It's only justified to use deadly force when you're approached with deadly force. If he had his hands in his pocket, and you shot him and you continue to shoot him, how is that justified if he had his hands in his pockets?" Angela Billups said.
The Chicago Police Department's account of the circumstances is that at approximately 8:30 p.m. Saturday, tactical officers in the Gresham District observed what they believed to be a suspicious vehicle conducting a drug transaction. They say Ontario Billups was in the car with his hands in his jacket. After numerous demands, they claim Billups refused to show his hands. Instead, they say, he got out of the vehicle and made an aggressive movement towards the officer, and that is when he was shot.
Chicago police Supt. Jody Weis said Sunday that people shouldn't be so quick to judge the police officer's actions.
"Don't draw a negative inference just because a weapon wasn't seen. Often times, if you wait for that weapon, you don't have time to take an action," Weis said. "I've never met a police officer or a soldier who wakes up in the morning and says, 'I hope I get a chance to kill someone today. That just doesn't happen.'"
The superintendent's words, however, are of little consolation to Ontario Billups' family.
"He was getting his life back on track. He had just recently received his GED. He was looking for a job. He was, basically, doing the right things out here," sister Trevia Jones-Gaines said.
Weis would not comment on the specifics of the case because it is under investigation. He did say, however, that while there are guidelines for police to follow before shooting a suspect, there are no specific rules because officers have to make split-second decisions.