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

A clerk who was 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.

Police on Wednesday arrested William McCormick, 19, and two accomplices, Michaela Lynn Minnocci, 20, of Ellwood City, and Christopher Michael Mangelli, 24, of Koppel.

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

On Wednesday as police questioned motel workers, Ms. Wheaton implicated her boyfriend and the other two suspects, a police affidavit said.

The three suspects who were 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 the money among themselves, police said.

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

The robbers entered the motel lobby and indicated they both were armed with guns as they demanded money from the till and the safe. They took $739, as well as Ms. Wade's purse containing a cell phone.

The three in custody each were held on $150,000 bail on charges including robbery, theft, kidnapping, unlawful restraint, making terroristic threats and conspiracy.

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