The archdiocese received the allegation about Mazzotta in May 2010, reported it to law enforcement, and made his name public. The incident happened more than 40 years ago, and the archdiocese said it was the only such claim received against him.
David Clohessy, director of SNAP, the Survivors Network of those Abused by Priests, questioned why both incidents took so long to be made public, especially as Campbell had reported on himself.
"How on earth can [Philadelphia Archbishop Charles J.] Chaput justify keeping silence about an admitted child molester for six months? God forbid if he has molested other kids during the months that Chaput kept his secret," Clohessy said.
Farrell responded to questions in the early evening Sunday but was not available later to respond to Clohessy's criticism.
The news comes as the Philadelphia District Attorney's Office is trying a major case involving allegations of child sex abuse by local priests. Msgr. William J. Lynn, a former secretary for clergy and the first church official nationwide to be tried for covering up child sex abuse, is expected to begin presenting his defense this week.
On May 4, Chaput said five priests had been found unsuitable for ministry due to substantiated claims of sexual abuse or other significant violations of the ministerial code. They were among 26 priests suspended over allegations after last year's grand jury report on clergy sex abuse.
Three other priests were cleared to return to ministry, and another died before the inquiries were completed. Decisions in 17 other cases are pending.
Mazzotta's and Campbell's cases were not among the pending ones, the archdiocese said.
Jack Howley, a parishioner at St. Maximilian Kolbe, said many in the pews cried Sunday when they heard the news about Campbell, which was announced at Mass. Campbell helped found the parish and oversaw construction and fund-raising for its elementary school, which opened in 2000.
"I'm as shocked as everybody else. There were definitely people who were really attached to him," Howley said. "Part of what I liked about him was his sermons were very short and to the point. He had a message. He ran a good parish, put a school in, and it grew and it grew and it grew. I grieve for him."
When the abuse incidents were reported, Mazzotta and Campbell were prohibited from exercising their public ministries, wearing clerical garb, or presenting themselves publicly as priests.
Mazzotta, 73, agreed to accept "a supervised life of prayer and penance, according to the release."
Campbell, 77, retired in 2007. He also agreed to accept a supervised life of prayer and penance.
Mazzotta was a parochial vicar, or assisting priest, at St. Joseph parish in Downingtown, from 1966 to 1971, his first assignment after ordination. He served in the same capacity at Stella Maris, at 10th and Bigler Streets.
After his time in Downingtown, Mazzotta served at Epiphany of Our Lord parish in Philadelphia and at St. Maria Goretti High School from 1971 to 1976; St. Gabriel, Philadelphia, from 1976 to 1978; St. Clement, Philadelphia, from 1978 to 1980; St. Eugene, Primos, from 1980 to 1985; St. Paul, Norristown, from 1985 to 1988; SS. Cosmas and Damian, Conshohocken, in 1988; St. Robert Bellarmine, Warrington, 1988 to 1990; Mother of Divine Grace, Philadelphia, 1990 to 1997; and St. Madeline, Ridley Park, 1997 to 2008.
Campbell was ordained in 1961. He served at the following parishes and schools: Nativity of the Blessed Virgin Mary, Media (1961-66); St. Agnes, West Chester (1966-68); Newman chaplain at West Chester University (1968-86); Newman chaplain at Chester County Hospital School of Nursing (1968-86); Newman chaplain at Cheyney University (1971-86); St. Maximilian Kolbe, West Chester (1986-2007).
The archdiocese said victims of sexual violence at any time should contact its Victim Assistance Office at 1-888-800-8780 or go to email@example.com.
Contact staff writer Miriam Hill at 215-854-5520, firstname.lastname@example.org, or follow on Twitter @miriamhill.