The second Roman Catholic Bishop of San Jose on Sunday personally apologized to parishioners for giving a convicted child molester permission to work at a parish festival last month.

Bishop Patrick McGrath appeared at Saint Frances Cabrini Mass and told the congregation called it was an "an unfortunate circumstance" that pedophile Mark Gurries was provided a letter which gave him permission to volunteer at the Saint Frances Cabrini parish festival, according to the San Jose Mercury News.

"I take full responsibility," McGrath said. "I pledge to you I will do everything in my power to make sure this doesn't happen again."

Gurries had served a year in jail for "lewd and lascivious conduct" with a minor under 14. He is currently on probation.

Melanie Borrelli, 19, had noticed Gurries at the festival because she was friends with the victim. Borrelli's father asked police to remove Gurries from the event, but they could not arrest him because California law allows sex offenders on school property if they have a written letter of permission from the school administrator.

In an open letter posted on the Diocese of San Jose website, McGrath explained that the letter had been a "mistake."

"Our policy is clear: no one who has been found guilty of sexual abuse of a minor or vulnerable adult can be hired as an employee or allowed to volunteer in any activity that involves children, young people, or vulnerable adults," he wrote. "How this happened is still a matter of continuing investigation on the diocesan level. Even before that investigation is concluded, I want to assure you that we will never knowingly allow such an occurrence to be repeated in the Diocese of San Jose."

Watch this video from KNTV, broadcast Nov. 16, 2012.

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(h/t: NBC News)