SKOWHEGAN — A former Pittsfield man was sentenced to serve 20 years in the Maine State Prison for sex crimes against a child under the age of 10, according to a news release from the Somerset County Sheriff’s Office.

Somerset County Sheriff Dale Lancaster said William Heiser, 61, now of Lewiston, pleaded guilty Nov. 9 to two counts of gross sexual assault, class A felonies.

As a Tier 3 lifetime registrant on the Maine Sex Offender Registry, Heiser will be under lifetime supervision when released. “This outcome is the result of a thorough investigation by the Somerset County Sheriff’s Office Criminal Investigation Division, Detective Jeremy Leal, and the efforts of Somerset County District Attorney’s Office,” Lancaster said in the release, which appeared on the sheriff’s office Facebook page.

Heiser was arrested on a warrant in May at his home.

Lancaster said the assaults took place from 2009 until 2012 in Pittsfield. Leal worked on the case with the Chittenden County Unit for Special Investigations in Burlington, Vermont, which provided a forensic specialist who interviewed the girl and obtained a full disclosure, he said.

The victim, now 16, made the allegations to a school mental health worker in Vermont, where she lives now, Lancaster said.

“The girl would have been under the age of 10,” Lancaster said. “These are extremely serious charges. These are significant charges, and the severity of these crimes do not minimize over time. These crimes have a lifetime emotional and physical impact on the victims.”

The investigation into the allegations led Leal to Lewiston, where Heiser was living. Leal, working with the Lewiston Police Department Detective Division, located and interviewed Heiser. During the interview, Heiser confessed to the assaults, according to Lancaster. After the interview, a warrant was granted by the court, and on May 12 the Lewiston Police Department arrested Heiser at his home. Heiser was taken to the Somerset County Jail in East Madison the following day.

Doug Harlow — 612-2367

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Twitter:@Doug_Harlow