Police investigators have arrested a 27-year-old West Ashley man on charges that he sexually assaulted a sleeping patient at Palmetto Lowcountry Behavioral Health Center in North Charleston.

Ricardo Cyril Powell of Gillins Lane faces a count of first-degree criminal sexual conduct, according to a report from the North Charleston Police Department. He was arrested Thursday in connection with the incident last week, police spokesman Spencer Pryor said.

He was being held at the Charleston County jail Friday in lieu of $200,000 bail.

Powell has a history of misdemeanor criminal convictions, according to the State Law Enforcement Division.

He served 18 months of probation after the Charleston Police Department found him with less than a gram of cocaine or methamphetamine in November 2008.

He spent some time in jail for third-degree assault and battery after the Charleston County Sheriff’s Office arrested him in September 2011.

Last month, he was arrested and later convicted of trespassing in North Charleston.

The police responded around 10:30 p.m. June 12 to the mental health facility at 2777 Speissegger Drive.

A patient told officers she awoke to the sound of a man groaning. She saw the man on his knees over her roommate, who was sleeping on her stomach.

He was exposed, the woman told investigators. He tried to force the witness to have oral sex, the incident report stated.

After she refused his advance, the woman said, she pushed the man from the room.

“Please don’t tell on me, please,” he said, according to the report.

The sleeping woman, 32, wasn’t aware of the assault until her roommate yelled at her to get up, she told police, because she had taken sleeping medication.

When she awoke, she was lying on her stomach, and her underwear had been pulled down around her knees. She complained of pain and was taken to Medical University Hospital.

After the incident was first reported, facility officials said patient confidentiality laws prevented them from discussing the incident but that they were cooperating with the authorities.

Reach Andrew Knapp at 937-5414 or twitter.com/offlede.