Chicago police say the suspect has a record of at least 50 other arrests.
This incident took place last Sunday in the 4500-block of North Sheridan. An 85-year-old man used his key to allow a stranger into the building. Seconds later, as the two rode the elevator, that mistake cost him dearly.
The attack was as fast as it was vicious. The elderly man was beaten then robbed and left in the elevator.
"It's upsetting and disconcerting," said Ronald Schupp, building resident.
Those who live in the building were finding a bit of relief Saturday, thanks to some observant police officers who watched security camera footage of the attack at a roll call.
"Without the video, I don't know if we would have made the arrest," said Chicago police Officer Bryan Boeddeker.
Boeddeker was patrolling Sheridan Road Wednesday, just a block from where the beating happened, when he saw a man he recognized from the surveillance tape.
"The high quality of the video really helped. He was wearing the exact same clothing. When I observed him, he was limping down the sidewalk," the officer said.
"In my 15 years, it was very hard to look at. You see the offender in a violent manner just [at the] start of the assault," Chicago police video technician Officer Nano Guardi said.
Dennis Dawson, 34, was in police custody Saturday charged with the robbery.
Police say the attack is a reminder of the important role security cameras can play in catching criminals. They say it is also a wake-up call for residents who may not think twice about allowing a stranger into their building.
"If someone rings the lobby bell, and you don't know them, don't let them in. If someone follows behind you , be aware of your surroundings. It's very important," said Cmdr. Kathleen Boehmer of the Chicago police.
"There was a couple of times someone didn't have a key, and I didn't let them in. I'd say sorry use your key," said building resident Mike Antoncew.
"I hope people will be more careful. It can be dangerous here," Schupp said.
ABC7 Chicago is told the elderly man is expected to be ok.