ST. LOUIS - An Uplands Park police officer faces up to 25 years in federal prison after admitting Wednesday that he robbed and sexually assaulted four female paid escorts he had lured to meet with him.

Leon F. Pullen, 32, of Foley, scoured online advertisements posted by the escorts, then pretended to be a customer, according to court documents and testimony at his plea hearing in federal court here. Three attacks occurred in the northwest St. Louis County village of under 500 people, one at a St. Louis hotel.

Once with the escorts, Pullen would identify himself as an officer, then demand money, sex or both by threatening arrest or the implicit threat of violence, Assistant U.S. Attorney Howard Marcus said in court.

Pullen pleaded guilty of nine felony charges, including conspiracy, deprivation of civil rights, witness tampering and lying to the FBI. In exchange, prosecutors will drop 10 other charges. He is scheduled for sentencing in October.

One of Pullen's victims, identified in court only as "D.S.," watched the hearing and spoke to a reporter afterward.

D.S., 36, said she had been in St. Louis with a friend last year for baseball's All-Star Game, and posted an ad on a website. Her account of the evening of July 15 was confirmed through court records and testimony, including Pullen's admissions in court.

Pullen arranged their meeting, agreeing to pay $400 for both D.S. and a friend. He drew them to an address that turned out to be an abandoned house in Uplands Park. When the women arrived, Pullen, in uniform, with a marked police car, and an auxiliary officer, Justin Biancardi, pulled them over.

Pullen told D.S. to give him all her money or get naked. When she offered money, Pullen told her, "That was the wrong answer," Marcus said in court. Marcus also said that Biancardi took money from D.S.'s friend.

Pullen then ordered D.S. to follow him. D.S. said that Pullen refused her requests for a lawyer or a female police officer, and that she panicked at the prospect of following Pullen to the station. She recalled her friend saying, "You have to go. He's a cop. You try to drive off, he's going to kill us."

Inside the station, Pullen forced D.S. to sit on a bulletproof vest and forcibly performed oral sex on her. "You're raping me, stop it!" she recalls shouting. Pullen then suggested intercourse, but neither had a condom. She was able to escape by suggesting that they meet later.

D.S., the former wife of a police officer, said she called St. Louis police internal affairs and was referred to the FBI. Within hours, agents were listening in as she called Pullen and confronted him about the sexual assault. She said he had written down his number for her, and she remembered his name from embroidery on his shirt.

Agents would later win the cooperation of Biancardi and collect Pullen's DNA.

In court, Pullen also admitted robbing and sexually assaulting women on three other occasions from February to June of 2009. He acknowledged that he lied to the FBI and told Biancardi to lie, saying that no one would believe the women because they worked as escorts.

Pullen was arrested by the FBI in September 2009 as he was about to start his shift. Officials said he had ads printed out for 11 other female escorts.

He has been on unpaid administrative leave since his arrest, said Douglas Rudman, a lawyer who represents Uplands Park. "Now that he has pleaded guilty, I anticipate the council at its next meeting will take appropriate action."

Rudman said that Biancardi, who was unpaid, left the department on his own before Pullen's arrest.

Biancardi's lawyer, David Ferman, said Wednesday that his client is no longer in law enforcement.

Ferman said he expects Biancardi to face unspecified federal charges later.

Gonzalo Fernandez, a lawyer representing three of Pullen's victims, was at Wednesday's hearing and said later that they may file a civil suit against the village.