Walker, 44, was arraigned in federal court yesterday on charges including robbery, extortion, false arrest, falsifying police paperwork and weapons offenses, before U.S. Magistrate Thomas J. Rueter. He is scheduled to appear for a probable-cause and bail hearing Tuesday.
Walker lumbered into federal court in a green prison jumpsuit and asked for a court-appointed attorney - a request Rueter quickly denied after seeing his police salary, which has topped $100,000 for years.
Police Commissioner Charles Ramsey suspended Walker yesterday with intent to dismiss.
Walker's ex-wife, Shakirah Gregory Walker, is also a Philadelphia police officer.
Court veterans say Walker's arrest could imperil hundreds, if not thousands, of pending and past drug cases. He is a fixture at the Criminal Justice Center, often testifying in narcotics cases.
"This will be another monumental dismissal of pending cases," Guy Sciolla, a longtime defense lawyer who has handled hundreds of narcotics cases, said yesterday.
"He has been one of the most active narcotics officers in the city for the last decade, so [District Attorney] Seth Williams will once again be confronted with the awful responsibility of having to recognize that a police officer, if capable of doing what he's alleged to have done, is not going to be reliable in any prosecutions that are open. [His arrest] is probably going to cast some doubt on cases in which he's already testified which resulted in convictions."
D.A. spokeswoman Tasha Jamerson declined to comment.
Assistant U.S. Attorney Anthony Wzorek said detectives are continuing to investigate because Walker's case "would suggest a pattern of conduct."
The investigation started when the witness alerted an FBI agent May 6 that Walker had asked for his help in robbing drug dealers, according to the affidavit.
During a series of meetings secretly monitored by the FBI, Walker directed the witness to distract the dealer by taking him out for drinks, so that Walker could plant drugs in the dealer's car, according to the affidavit. After police arrested the dealer, Walker said, he could steal the man's keys and together, he and the witness could rob the dealer's vacant home, the affidavit reads.
Walker did just that on Tuesday, authorities said.
But when the accomplice took the dealer to Spiro's Bar, on Girard Avenue near 40th Street in West Philadelphia, FBI investigators were secretly watching - and monitored Walker's alleged con as it unfolded.
After his arrest outside the dealer's home, on Florence Avenue near 57th Street in Kingsessing, Walker admitted that he planned the false arrest, planted 28 grams of cocaine in the dealer's car, took the man's key, broke into his house and stole $15,000 in cash, authorities said.
Authorities declined to name the alleged dealer and cooperating witness.
On Twitter: @DanaDiFilippo