A repeat sex offender from Somerset County who was convicted in March for molesting a 15-year-old girl has been sentenced to five years in prison for violating Megan’s Law by working as a youth minister and counselor at a church, authorities said Monday.

The sentence will be added to the five years that Shawn Butler, 53, of Hillsborough, is already serving for child endangerment and criminal sexual contact, according to Somerset County Prosecutor Michael H. Robertson.

Butler was found guilty on May 21 of third-degree prohibited participation in a youth serving organization. He worked as a youth counselor, youth mentor, and youth chaperone for a religious center in Franklin Township, authorities said.

Butler worked at Eternal Life Christian Center and served on the church's executive board. At trial, Assistant Prosecutor Thomas Carver made the case that Butler improperly touched a 15-year-old girl in South Brunswick and at his home in Hillsborough several times between March and June 2014.

Authorities said he took the position at the church even though he was convicted in 1990 of sexual assault in Middlesex County. He was sentenced to seven years in prison on that offense, which occurred while he was still on probation for a 1988 criminal sexual contact conviction.

Robertson stated that due to the 1990 sexual assault conviction, Butler was prohibited from participating in youth serving organizations.

The children that he counseled, mentored, and chaperoned were between the ages of 12 to 17 years old, the prosecutor said.

“Butler worked with these children by supervising and mentoring them at various youth ministry events (and) activities, including overnight camps, concerts, outings, and youth groups,” Robertson said.

Robertson and Fodor ask that anyone with information about Robertson call the Somerset County Prosecutors Office Sex Crimes/Child Abuse Unit at 908-231-7100 or the Franklin Township Police Department at 732-873-5533.

Anthony G. Attrino may be reached at tattrino@njadvancemedia.com. Follow him on Twitter @TonyAttrino. Find NJ.com on Facebook.

Get the latest updates right in your inbox. Subscribe to NJ.com’s newsletters.