Walker pleaded guilty to attempted robbery and carrying a firearm during a crime of violence for stealing $15,000 from a drug dealer's home last spring.
Walker, a 24-year police veteran who worked in the Narcotics Field Unit since March 1999, faced up to a lifetime in prison and $500,000 in fines, but decided to plead guilty in hopes of landing a lighter sentence.
U.S. District Judge Eduardo Robreno scheduled his sentencing for May 21 - which, ironically, was the one year anniversary of the FBI sting that resulted in Walker's arrest.
But Assistant U.S. Attorney Anthony Wzorek afterward said he expects the sentencing will be postponed until after the trials of other suspected dirty cops and civilians against whom Walker will testify.
"It's outrageous behavior," Wzorek said of Walker's scheme. "It's offensive to the city and the other honest members of the police department."
Authorities caught Walker after an informant alerted the FBI in early May that Walker had asked for his help in robbing drug dealers. FBI agents set up a sting, and after his arrest, Walker admitted he planted 28 grams of cocaine in the dealer's car, stole his keys, broke into his Kingsessing house and stole $15,000 in cash.
A judge overturned more than 50 drug-related convictions because of Walker's involvement, while the District Attorney's Office withdrew at least another dozen drug cases involving Walker.
Police Commissioner Charles H. Ramsey last month stripped five other longtime narcotics officers of their police powers, removing them from street duty and taking their department-issued firearms, because they are the subject of a federal grand-jury probe.