The man who authorities say masterminded the gang rape of a Potomac woman in her home last year pleaded guilty yesterday to rape, burglary and armed robbery before a Circuit Court judge in Rockville.

Gujuan A. Lee, 19, of the District and two other males sexually assaulted the 19-year-old woman Sept. 6, 2004, after breaking into her house in what authorities described as a chillingly premeditated crime.

"The nature of the planning strikes me as particularly insidious," Montgomery County State's Attorney Douglas F. Gansler said after the plea hearing.

Prosecutors said five suspects, wearing ski masks and bandannas, were able to sneak into the woman's residence on Falls Chapel Way using a key one of them stole days before when he attended a party at the home. Once inside, Lee threatened the woman with a gun and forced her to have sex, prosecutors said. Two of the other men also assaulted her, authorities said.

Loyd Byron Hopkins, Lee's attorney, disputed prosecutors' characterization of his client's role in the crime.

"That's a joke," Hopkins said, adding that Lee believed he was having consensual sex with the victim that morning because he was under the influence of drugs and has mental problems. "He's the least intelligent of all of them."

Lee pleaded guilty because "it was the best deal he could get under the circumstances," Hopkins said.

The other four men who broke into the house with Lee have also pleaded guilty in connection with the case.

Judge James L. Ryan scheduled Lee's sentencing hearing for Nov. 23. Lee faces up to two life sentences plus 40 years.