The extortion was revealed during the investigation into another embarrassing incident for Atlanta police: the fatal 2006 police shooting of an elderly woman in a botched drug raid.

Daniel Betts, who resigned from the police force Wednesday, pleaded guilty to one federal count of interfering with interstate commerce by means of extortion under color of official right.

Betts admitted taking payoffs from the owner of the complex, which functions as a rehabilitation facility for recovering drug addicts. Prosecutors said he took $120 a week from the apartment owner over at least a four-month period last year.

Betts, 26, told U.S. District Judge Julie Carnes he didn't know his conduct was illegal at the time, but he does now.