A South Nyack man faces up to seven years in prison after being convicted Thursday of sexually abusing a friend's 4-year-old daughter while baby-sitting.

Todd Retallack, a former Rockland County church youth group leader, was found guilty of first-degree sexual abuse, a felony, and endangering the welfare of a child, a misdemeanor.

Retallack, 49, molested the girl at her home during the fall of 2009. He was arrested in May 2011 following a six-month investigation triggered by a complaint from the girl's father. Retallack was friends with the girl's family.

The victim, now 7; her mother; and Retallack's daughter, a friend of the girl, testified against Retallack, a self-employed computer graphic designer. The 11-person jury returned the verdict after deliberating for eight hours.

"This defendant was convicted of having betrayed the trust of a young child and her family," Rockland District Attorney Thomas Zugibe said in a statement. "No child should be put in that position. The jury ... heard the evidence in the case, which rested largely on the testimony of the now-7-year-old victim. Children should be able to remain children."

Retallack's lawyer, Daniel Bertolino, did not immediately return a call seeking comment Thursday night.

Retallack will be sentenced Sept. 11. He faces two to seven years in prison.