The ‘Bare-Chested Bandit’ on a CTA train following his Sept. 16 bank heist. The robber has hit three banks in the Chicago Loop since mid-September. (FBI photos)

The FBI-Chicago Field Office is seeking the public’s assistance in identifying the “Bare-Chested Bandit,” a robber who has hit three banks in the Chicago Loop since mid-September.

Though the offender has worn a different “disguise” for each incident, FBI agents said it is the first time in recent years where an offender changed clothes on public transportation.

The bandit was shirtless on a CTA train after one of the robberies, earning the “Bare-Chested Bandit” moniker.

Shortly before 4 p.m. Tuesday, the FBI and Chicago police responded to a robbery at Citibank, located at 100 S. Michigan Ave.

The same offender robbed the Citibank at 180 N. Michigan Ave. at 9:47 a.m. Sept. 16 and 2:25 p.m. Sept. 19.

In the Tuesday incident, the offender approached a teller and passed a note demanding funds. He made a violent threat before obtaining funds and fleeing.

The bandit following the Tuesday bank heist

The robber was described as a white man, 30-40 years of age, 5’6” or 5’7”, with a medium build, an armband tattoo on his upper right arm, and wearing a dark plaid patterned jacket, white shirt with collar, light-colored jeans, black hat, mirrored sunglasses with a black frame, and black and white athletic shoes.

In the Sept. 16 robbery, he wore a black and white patterned hoodie, black pants and black shoes.

For the Sept. 19 heist, the offender wore a green hat, sunglasses and a black zip-up hoodie.

No injuries were reported in any of the robberies.

FBI agents said the individual should be considered armed and dangerous.

The FBI is offering a reward of up to $1,000 for information leading directly to the arrest and conviction of the robber.

Anyone with information regarding the bank robberies or the offender should contact the FBI’s Chicago Field Office at 312-421-6700.

Tips can be submitted at tips.fbi.gov.