Father John Hammer was ordained on June 23, 1979. There are several credible counts of sexual abuse against Hammer. In 1985, Father Hammer was dismissed from the Diocese of Youngstown amid allegations of child sex abuse. Following a year of treatment at St. Luke Institute and three years at St. Agnes Hospital in Maryland, he was moved to the Saginaw Diocese in Michigan, where he reportedly abused another child at St. Louis during the 1990s.
In 1988, Hammer was allowed to live in the rectory instead of St. Agnes so long as he was not involved with the parish and paid for room and board. He was forced to resign in 2002 when his abuse was made public.
| Date | Position (If Available) | Church/Organization | Location |
| 1979-1983 | Associate Pastor | St. Louis | Louisville, OH |
| 1983 | Student | University of Notre Dame | South Bend, IN |
| 1985 | Associate Pastor | St. Columba Cathedral | Youngstown, OH |
| 1985 | Associate Pastor | St. Aloysius | East Liverpool, OH |
| 1985-1986 | Patient (Treatment) | St. Luke Institute | MD |
| 1986-1989 | — | St. Agnes Hospital | Baltimore, MD |
| 1990-1991 | — | St. Stephen | Saginaw, MI |
| 1991-1995 | Associate Pastor | Blessed Sacrament | Midland, MI |
| 1995-1999 | Pastor | Mount St. Joseph | St. Louis, MI |
| 1995-1999 | Pastor | St. Patrick | Irishtown, MI |
| 1999-2002 | Pastor | Mount St. Joseph | St. Louis, MI |
| 1999-2002 | Pastor | St. Mary | Alma, MI |
