Prosecutors allege that 27-year-old Mark Williams conspired with other officers and a drug dealer to rob a heroin supplier and share the profits.
During testimony Tuesday, an undercover drug agent says the scheme got off to a slow start because the officers were suspicious, but they eventually took the bait.
Assistant U.S. Attorney Anthony Wzorek said in opening statements that Williams violated his oath and "became a drug dealer." But defense attorneys Anna Durbin and Joseph Valvo told jurors to be skeptical of what they hear about Williams and his co-defendant, Zachary Young.
Two other former officers, 30-year-old Robert Snyder and 32-year-old James Venziale, earlier pleaded guilty and are to be sentenced in May.