ROCKLAND, Maine — A former Knox County Jail guard will spend 60 days in jail after being convicted Tuesday of sexually assaulting a female inmate more than two years ago.

Justice John O’Neil sentenced Adam Grierson, 27, to 15 months in jail with all but 60 days suspended for one count of gross sexual assault. The former guard also will be placed on probation for two years upon his release.

Grierson pleaded no contest, which results in a conviction without an admission of guilt, thus allowing the defendant to contest the charge in a civil case. Two other gross sexual assault charges against him related to the same victim were dismissed as part of the agreement between the defense attorney and prosecutor.

District Attorney Geoffrey Rushlau said the crime became known in July 2013, when the victim filed a federal civil rights lawsuit against Grierson and Knox County. When that lawsuit was filed, the Knox County Sheriff’s Office asked Rockland police to investigate the allegation.

Grierson already had been placed on administrative leave in 2012, after being accused of providing cigarettes to the woman. Following an internal investigation, he was charged with trafficking tobacco and resigned. The trafficking case later was dismissed.

The allegations of sexual assault did not come to light until the former female inmate filed her civil rights lawsuit.

The victim is seeking $300,000 in damages as well as unspecified punitive damages. No trial date is scheduled for the civil case filed in U.S. District Court in Portland.

The Bangor Daily News is not naming the woman because she is considered a victim of sexual assault.

The woman, who was an inmate at Knox County Jail from November 2011 through April 2012, told Rockland police that in exchange for sex, Grierson provided her with cigarettes he smuggled into the nonsmoking facility. In Maine, it is a felony for corrections officers to sexually assault an inmate under their supervision. The maximum sentence for Class B gross sexual assault is 10 years in prison.

Grierson acknowledged the sexual encounters but denied it was in exchange for cigarettes. Two other counts of gross sexual assault against Grierson related to the same victim were dismissed as part of the agreement reached between the prosecution and defense.

Grierson remains free on bail. Justice O’Neil agreed to allow Grierson to report to jail Oct. 1 at the request of his employer.

Grierson is the second Knox County Jail guard accused in the past year of sexually assaulting female inmates.

Richard S. Wellington, 61, was indicted in April on two counts of unlawful sexual contact and 17 counts of unlawful sexual touching. The indictments list three different victims, with the assaults beginning in November 2012 and ending in August 2013.

Wellington was hired as a part-time corrections officer in April 2012 and was terminated in August 2013. He previously worked at the Maine State Prison.

Wellington has pleaded not guilty to the offenses. No trial date has been scheduled.

To reach a sexual assault advocate, call the Statewide Sexual Assault Crisis and Support Line at 800-871-7741, TTY 888-458-5599. This free and confidential 24-hour service is accessible from anywhere in Maine. Calls are automatically routed to the closest sexual violence service provider.