A 26-year-old Auburn man has been indicted on 18 counts of unlawful sexual contact for allegedly molesting a female family member under the age of 12, according to court records.

Tyler Briggs was indicted by the Cumberland County grand jury Friday after the family member told her mother in January that Briggs had been molesting her when he baby-sat for the girl.

Although the indictment lists 18 counts, one investigator initially believed there could have been at least 100 incidents starting in September 2014.

The assaults began about two years ago, when Briggs began caring for the child when her mother was working or running errands, according to documents filed at the Cumberland County Courthouse.

The 18 counts cover 18 consecutive months, during which time Briggs is alleged to have abused the child multiple times per week in Windham, and once in Standish.

According to police interviews with family members summarized in court records, Briggs touched the girl under her clothes, usually when he and the child were lying down together watching something on a tablet computer.

The girl eventually reported the abuse to her mother, who brought the child to the emergency room at Maine Medical Center. Doctors examined the girl and police were called.

Briggs was arrested Jan. 23 in Auburn, the same day the girl reported the abuse. Since then, he has been held at the Cumberland County Jail in Portland.

When police asked Briggs if he knew why they were there, “he kind of grunted yes,” according to a police report. Briggs declined to be interviewed by police, invoking his Fifth Amendment right to remain silent.

Briggs is expected to be arraigned on March 21.