PORTLAND — An 18-year-old Portland man faces charges of gross sexual assault and burglary after his arrest Sunday.

Police charged Mohammed Mukhtar in connection with an attack at about 3 a.m. Saturday on a 50-year-old woman in an apartment on High Street in the Parkside neighborhood. The two did not know each other, police said.

Mukhtar climbed into the apartment building through an open window, bypassing the locked front door, then went into the woman’s apartment which was not locked, police said.

The woman was asleep when the attack began, but after she confronted the suspect, he ran out the front door, police said.

Police were able to develop Mukhtar as a suspect over the course of the investigation and arrested him at 10 a.m. Monday at his home on Danforth Street, police said.