Authorities said it was the first incident in recent years in which they've observed a suspect changing clothes on public transportation.

The suspect, a man in his 30s, is accused of robbing three banks in the Loop since Sept. 16. He was apparently seen on surveillance changing clothes on public transportation after a robbery.

CHICAGO (CBS) – The FBI is offering a $1,000 reward for information leading to the arrest and conviction of a man who robbed a bank in the Loop Monday morning. Authorities responded to the Citibank just before 10 a.m. in the 100 block of North Michigan Avenue. The suspect walked in, displayed a demand note, and implied that he had a handgun.

The FBI is asking for the public’s help in identifying a bank robbery suspect, known as the "Bare-Chested Bandit," who is believed to have carried out three heists in the Loop since mid-September.

The FBI’s Chicago Office is looking for a man they’ve dubbed the “Bare-Chested Bandit,” who has committed three bank robberies on the 100 of North Michigan in recent weeks.

The FBI’s Chicago Field Office is investigating a bank robbery that unfolded in the Loop on Tuesday afternoon and it may be just one of several robberies committed by a man who agents are calling the “Bare-Chested Bandit.

The Federal Bureau of Investigation Anchorage Field Office is seeking any information regarding an unidentified suspect in an attempted bank robbery at the Credit Union 1, Midtown Branch, located at 3525 Eureka Street in Anchorage.