AUGUSTA — A Windsor man on Tuesday admitted to sexually abusing a young girl over an eight-year period from 2001 to 2009.

Richard M. Libby, 48, pleaded guilty to four charges each of gross sexual assault and unlawful sexual contact, all of which name the same girl as victim and say she was under 12 and later 14 years of age when the offenses occurred.

Seated in the back of the small courtroom at Kennebec County Superior Court with a victim advocate, the victim’s mother watched the plea and left in tears at the end of the hearing.

Libby had been scheduled for a jury trial on Thursday and Friday, and his guilty pleas mean that no longer will occur. Justice Michaela Murphy accepted the pleas and said he would be sentenced at the end of January.

She told him the five class A offenses carry maximum terms of 30 years in prison and that he could be ordered to serve the sentences on each count concurrently or consecutively.

Libby, who spent most of the hearing with his head bowed and eyes on a table or the floor, said he understood that. Libby’s responses — mostly yes or no answers — occasionally were muffled by noise of heavy equipment operating a few feet from the courthouse.

He also told the judge he suffered from head trauma, which his attorney, William Baghdoyan, said occurred when Libby was 17 or 18 years old. Baghdoyan also said Libby had undergone a competency examination by the State Forensic Service.

A week ago, a judge denied Libby’s attempt to suppress an audiotape of a conversation with a Kennebec County sheriff’s detective in which Libby confessed to having sexual contact with the girl but insisted he never had intercourse with her.

Libby maintained that conversation occurred when he had been up most of the night and after an acquaintance slipped three prescription pills into his Coca-Cola. He testified he had just wanted the detective to go away.

In exchange for Libby’s guilty plea, the prosecutor dismissed four more charges each of gross sexual assault and unlawful sexual contact. Earlier, six misdemeanor charges of unlawful sexual touching against Libby were dismissed as well.

The prosecutor, Deputy District Attorney Fernand Larochelle, said the victim, who is now an adult, would testify that the abuse began when she was 4, occurred several times a week and escalated to intercourse by the time she was a second-grader.

Larochelle said the victim said Libby threatened to hurt her and her family if she told anyone what he was doing.

When she was in eighth grade, the girl told a friend about it, and later a sibling. However, Larochelle said the girl never told her mother.

“As she got older, she tried to avoid the defendant as much as she could,” Larochelle said, adding that she tried to resist Libby but was mostly unsuccessful.

Betty Adams — 621-5631 badams@centralmaine.com Twitter: @betadams