A retired detective with the Chicago Police Department has turned in his nephew to the FBI in connection with a bank robbery Wednesday at the Aon Center.

The next day, the retired detective called an FBI employee, saying his nephew, Ramses Longstreet, had robbed the Associated Bank branch at 200 E. Randolph St., according to a criminal complaint filed Thursday in federal court.

The robbery at the iconic downtown building happened around 8 a.m. Wednesday. A man asked a teller for change for a $10 bill, started to walk away after being told he had to have an account there, then jumped onto the counter and demanded money, authorities said. He patted his waistband and said he had a gun but didn’t show a weapon.

The robber emptied a cash drawer and left with more than $2,800, according to the FBI.

Surveillance images showed him wearing a yellow, hooded sweatshirt emblazoned “IOWA.”

Longstreet, 42, went to his uncle hours after the robbery, asking him to hold $2,600 for him, the complaint says.

After Longstreet left, his mother called the retired detective, telling him someone from the rehabilitation center where Longstreet was living had called her, saying her son had robbed a bank, the complaint says.

The former detective called his nephew, not telling him why but arranging to pick him up, then drove him to FBI headquarters, authorities said.

Tellers at the bank identified him, and some of the cash he gave his uncle included bait bills from the bank, the complaint says.

Longstreet is being held at the Metropolitan Correctional Center.