BRADENTON, Fla. -- Three officers have resigned after an investigation revealed they had had sex with prostitutes and some exchanged drugs for the encounters, police said Wednesday.

Former police officers Pete Biddlecome, William Anderson and Larry Jeff Pritchett all resigned in June over the allegations. Pritchett and Biddlecome had been assigned to the department's Safe Streets Unit, in which undercover officers fight prostitution and drugs. Anderson was a patrol officer.

Prostitute Dawn Marie Gibson passed a lie-detector test of her claims that she had sex with Biddlecome and another police officer in a police substation and a police car. She also claimed she had sex with Pritchett several times in exchange for drugs and money.

Biddlecome admitted he had sex with Gibson in a rental car in 2005, which was used for undercover work, according to police documents.

Gibson's friend and fellow prostitute Sarah Wysocki said she had sex with Anderson in a police substation, the reports said.

Authorities also were investigating whether the officers' supervisors knew about the conduct, Chief Michael Radzilowski said.

Biddlecome told The Herald of Bradenton that he did not know Gibson was a prostitute. He said he found out a year after she was arrested for prostitution.

"I am a good cop that made a stupid mistake," Biddlecome told the newspaper. "I told the truth and am dealing with the consequences. I regret what I did, everyday."

Captain Russell Tibbitts said the agency strives to be professional and responsive to the community.

"This is a very unfortunate event. The three accused officers no longer work here," Tibbitts said.

A woman answering the telephone at a listing for Pritchett said it was the wrong number. A telephone number for Anderson could not be located.