CASTLE ROCK, Colo. — A convicted sex offender has been sentenced to 70 years to life in prison for assaulting three children in a Highlands ranch home.

Forty-one-year-old John Cornell had pleaded guilty Oct. 20 to four counts of sex assault on a child by a person in a position of trust.

Douglas County District Judge Shay Whitaker sentenced Cornell on Friday. Prosecutors announced the sentence on Wednesday.

Prosecutors say Cornell had a previous sexual assault case. He was on parole when the child assaults occurred in the home of a Highlands Ranch woman. Two of the woman’s children and a niece were assaulted.

Prosecutors say the woman was sentenced to 30 days in jail after pleading guilty in June to evidence tampering by helping destroy pornographic photos Cornell had taken of the children.