Deadly Sins (1995)

New area deputy Jack Gales arrives on the island to find that a girl at the local Catholic girls' school has been found dead. After investigating, he finds that students have been disappearing regularly for five years, about the time Mother Bernadette passed away. Gales and the Mother Superior's secretary Cristina work together to try and unravel the mystery, and discover that the students and faculty all seem to have some secrets.