THOMASTON, Maine — A 65-year-old Thomaston man earlier this month pleaded guilty to six counts of sexual assault against four minors.

Robert J. Robinson was sentenced to 20 years in prison after pleading guilty on Jan. 12 to two felony charges of gross sexual assault, two felony charges of unlawful sexual contact and two misdemeanor charges of unlawful sexual touching, according to Knox County Unified Criminal Court documents.

Complaints against Robinson, a former animal control officer and traffic control officer for Thomaston, first were filed last spring, when the mother of one of the victims reported that Robinson had sexually assaulted her daughter, who was 10 at the time when the assaults began.

Robinson was arrested as a result of the first complaint in early April 2016 and then arrested a second time later in the month on additional charges of sexually assaulting two other girls. Robinson reportedly used to baby-sit at least one of his victims and attended Thomaston Baptist Church with others.

In a letter to the family of one of the victims, a copy of which is contained in the court file, Robinson apologized for “the problem that I caused” and said his behavior was not intentional.

“It was a mistake on my part, and I do seek forgiveness for it,” Robinson wrote.