HARRISBURG — A former Pennsylvania state trooper was convicted of helping truck stop pimps and prostitutes by tipping them off about police operations.

Shawn C. Dillard, 39, of Harrisburg, was convicted by a federal jury on Thursday of aiding interstate prostitution, obstruction and lying to investigators. He was acquitted of extortion and conspiracy.

Prosecutors said he warned prostitutes about undercover operations and law enforcement sweeps at an Interstate 81 truck stop and that he accepted money and sexual favors in return for leniency. Authorities said his actions allowed the ring that prostituted children as young as 12 years old to continue.

His arrest was part of Operation Precious Cargo, which identified pimps, most with ties to Toledo, Ohio, involved in the nationwide prostitution of young women and underage girls. So far it has resulted in the convictions of two former state troopers, 15 pimps and two chief prostitutes.

A federal judge scheduled Dillard's sentencing for August. His lawyer, Bill Tully, did not immediately return a phone message left at his office seeking comment.