A fired cop in Philadelphia pleaded guilty today to corruption charges stemming from a FBI sting.

Jeffrey Walker, a 24-year police veteran who worked in the Narcotics Field Unit, approached a cooperating witness last year with a plot to rob an alleged drug dealer. In May, Walker planted cocaine in the target's car, took a house key, and then used it to steal about $15,000 in alleged drug proceeds from that person's home. 

Walker was arrested immediately. He pleaded guilty in federal court to attempted robbery and carrying a firearm during a crime of violence.

"It's outrageous behavior," said Assistant U.S. Attorney Anthony Wzorek, who prosecuted the case. "It's an affront to the citizens of the city and to the other honest members of the Philadelphia police department."

Thomas Fitzpatrick, Walker's defense attorney, said his client is cooperating with authorities as part of an ongoing investigation. Fitzpatrick said he believes the probe will result in "a significant amount of indictments" and "significant police corruption being uncovered in this city."

"Jeffrey Walker is a good man. He's a good man who made terrible mistakes," said Fitzpatrick. "Today, he's made it back to the center of what that really means to protect and serve, and that's what he's doing for the citizens of Philadelphia by cooperating and by helping the government take bad cops off of the street."

Fitzpatrick did not provide details about the alleged wrongdoing, only noting that it is more serious than Walker's crimes. 

Wzorek confirmed that Walker has been cooperating with authorities, but he would not comment on the nature of the federal government's investigation.

Walker faces a maximum sentence of life in prison and $500,000 in fines. His sentencing is scheduled for May.