A 46-year-old man was sentenced on Thursday to 16 years behind bars for repeatedly sexually abusing his biological daughter for over a decade.

The father of the victim, whose name was not released to protect the child, pleaded guilty in April to course of sexual conduct against a child.

Prosecutors say he started sexually abusing his daughter in January of 2014, when she was just 6 years old. The abuse continued for years, either when family members were not home or when they were sleeping.

The victim told her brother and mother about the abuse in August last year. Her mother contacted the police and the father was arrested the following day.

“A father is supposed to protect his child. Period,” said Suffolk District Attorney Ray Tierney.