JANESVILLE — A 26-year-old man thought he was doing a good deed when he gave a 70-year-old woman a ride to a Minnesota bank.

But police say the woman robbed the bank, and the man driving a Jaguar was her unsuspecting getaway driver.

The man said he thought the woman, who rents an apartment from his mother, was going to the bank to withdraw cash to pay her rent.

Instead, employees of the Elysian State Bank reported Wednesday that an “elderly woman” told the teller she had a gun, demanded money and left with an undisclosed amount. A bank vice president followed the car and called authorities.

Police stopped the car in Janesville and took both people into custody. But they quickly determined the woman acted alone and used the unwitting driver.

“I think his eyes were pretty well open when they made the stop (at the bank),” Le Sueur County Sheriff Tom Doherty said.

Officers assumed both people in the car were armed and ordered them out of the car at gunpoint. Eventually the man was interviewed by sheriff’s investigators and was about an hour into his interview before he realized the woman was accused of robbing the bank, he said.

Police searched the car and found the bank’s cash. The woman had some ailments and was “down on her luck, trying to stay in her apartment,” the sheriff said.

The woman didn’t have a gun but did have a hammer in her bag. She’s in jail, pending charges.