The robbery this week of a Red Roof Inn in Cranberry was an inside job, township police said.

A clerk who had been alone on duty at the time of the robbery at 4:45 a.m. Tuesday told police she recognized one of the robbers as the boyfriend of a co-worker at the motel.

Yesterday, police arrested the co-worker's boyfriend, William McCormick, 19, and two alleged accomplices, Michaela Lynn Minnocci, 20, of Ellwood City, Lawrence County, and Christopher Michael Mangelli, 24, of Koppel.

Charges are pending against Mr. McCormick's girlfriend, Brandi Jo Wheaton, 26, of North Sewickley. Police have sought an arrest warrant, but Ms. Wheaton had not been arrested or arraigned today.

On Wednesday, as police questioned all of the motel's workers, Ms. Wheaton implicated her boyfriend and the other two suspects, according to a police affidavit.

The three suspects arrested all admitted participating in the holdup. They also said Ms. Wheaton, who previously had not been a suspect, was part of their conspiracy.

The four split up the money among themselves after the robbery.

The affidavit said Ms. Wheaton recommended the robbery at Red Roof because there would be a low risk of being caught, they expected a high payoff, and because she did not like the clerk who was on duty, Lisa Wade.

Two robbers entered the motel lobby and indicated they both were armed with guns as they demanded money from the till and the safe.

While the thieves waited until the time-release safe could open around 5 a.m., they locked the front doors to the lobby to prevent anyone from interrupting, police said.

The robbers took $739, as well as Ms. Wade's purse containing a cell phone. Her loss was about $550, police said.

The three suspects in custody each are being held on $150,000 bail on charges that include robbery, theft, kidnapping, unlawful restraint, making terroristic threats and conspiracy.

A preliminary hearing is set for 11 a.m. next Friday in Butler.