Pittsburgh police patrolling the North Side early Tuesday stumbled across a twisted tale of interstate child prostitution, sex abuse and drug addiction, according to the FBI.

As a result, a man and woman from Warren, Ohio, were hauled in to U.S. District Court yesterday to face federal charges of transporting a 15-year-old runaway from Warren to Pittsburgh to sell her to a man for sex in exchange for cocaine.

Greg Lowery, 44, who has an extensive criminal record in Warren, and Pamela Tilley, 45, could face at least a mandatory five years in prison if convicted.

Both had initial appearance hearings before a magistrate, who ordered them held until a Monday detention hearing at which more details of the case should emerge.

Both said they had no assets or jobs and couldn't afford lawyers.

U.S. Attorney Mary Beth Buchanan said the FBI and city police are still trying to piece the case together.

She would not discuss any specifics, including how and when Lowery and Tilley met or their relationship to the 15-year-old girl and a 13-year-old girl who also was traveling with them.

According to an FBI affidavit, city police on patrol on East Ohio Street came across Tilley's parked Saturn sport-utility vehicle at 12:30 a.m. Inside, they found Lowery, Tilley and the two girls asleep.

Tilley told officers she and Lowery had driven to Pittsburgh intending to "make the 15-year-old female available for prostitution," wrote FBI Agent Donald Kirk Duran.

She said the two had arranged to sell the girl to a city man, whom Buchanan would not identify.

Tilley, who said she and Lowery had been using crack cocaine and alcohol, also said the two had a sexual relationship and that Lowery had previously had sex with both girls with her consent.

In addition, according to the affidavit, she had sex with the 15-year-old girl, too. Just before the trip to Pittsburgh, she told agents that Lowery had used his cell phone camera to take pictures of her and the girl performing oral sex.

The 13-year-old girl, who is listed as an escapee from a juvenile placement center in Ohio, also confirmed that she has had sex with Lowery.

But according to the affidavit, Lowery told agents that it was Tilley's idea to sell the 15-year-old into prostitution in Pittsburgh.

Both are being held in the Allegheny County Jail. Buchanan said the girls are in foster care.