According to the FBI, which is handling the case, Chicago resident Charles B. Estell, 38, was charged with one count of felony bank robbery after authorities say he was found early Sunday, hiding in a strip mall at 111th Street and Pulaski.
The arrest followed an 11-hour standoff and search.
Authorities say a district court judge ordered him held without bond Sunday.
It all started at about 2:15 pm Saturday afternoon at the Bank of America in the 4000-block of West 111th Street in Oak Lawn.
Police say the gunman dropped into the bank through the roof, bound two employees with zip ties and duct tape, stole money, then tried to get away. He was spotted on security video.
An FBI spokesperson says Oak Lawn police were alerted to the robbery by an alarm and surrounded the bank before Estell was able to exit. He allegedly saw the police waiting for him outside and attempted to hide inside the building to avoid capture.
Nearly 70 law enforcement officers combed the area. Police went from building to building looking on the roof of each floor, even removing ceiling tiles and looking in the ductwork. They found an area where some money was kept and found blood at a broken window. After hours of looking for him and surrounding the bank, police finally found the man at 12:30 a.m. Sunday.
"SWAT team members from the south suburban emergency response team located the robber on the second floor in an air duct vent, wedged so tight that they had to cut him out of the vent," said Michael Kaufmann, division chief, Oak Lawn police.
Buses in the area were rerouted because of the activity. Nearby businesses were evacuated, and some were put on lockdown.
Some customers were so close to the action, they got a glimpse of the suspect moving around.
"Someone started saying, 'Hey, we can see him through the window.' He was crawling on his hands and knees like a dog. He had a cell phone in one had and a pistol in the other hand," witness Conrad Rusin said.
"We had a vantage point where we could see guy crouching down crawling around ...like he was asking somebody for advice or something," said Juanita Rusin, also a witness.
Police inside the strip mall said they could not believe what happened in broad day light. Crime scene tape was still visible around the bank later Sunday morning.
Estell is accused of having stuffed as much as $100,000 into a black backpack he is said to have carried with him. A black bag containing a large amount of cash was discovered on the roof of the building Sunday, authorities said.
Estell is scheduled to appear in court Tuesday afternoon. If convicted, he could face up to 20 years in prison.