NORRISTOWN, Pa. — Prosecutors in Pennsylvania on Tuesday crossed their final hurdle to bring Bill Cosby to trial on charges that he drugged and sexually assaulted a woman he once mentored, with a judge ruling that enough evidence existed for the case to move forward.

While Mr. Cosby is fighting numerous civil cases involving similar accusations, the ruling, by Judge Elizabeth A. McHugh, means that the once popular entertainer must face at least one of his accusers in a criminal proceeding, likely to take place here this year.

“This case will move forward,” Judge McHugh told the crowded courtroom in Montgomery County Courthouse.

The hearing, while routine, attracted widespread attention, with more than 100 members of the news media and public packed into the courtroom, and 50 others were seated in an overflow room nearby.