WATCH: Trailer for Netflix documentary series The Keepers, released May 19

The Keepers is a seven part Netflix original documentary series, which explores the unsolved murder of the nun Sister Cathy Cesnik who taught English and drama at Archbishop Keough High School, in Baltimore, almost 50 years ago.

The Catholic high school teacher went missing November 7, 1969 and her body was found nearly two months later—yet her death remains unsolved.

Sister Cathy’s former students have long believed that the nun was murdered to prevent her from speaking out about the sexual abuse of children by the school’s priest, and the authorities, along with the Catholic hierarchy, covered up her death.

The series attempts to uncover the truth about this dreadful crime, that went largely unreported outside of Baltimore at the time.

The series will be released on Netflix on May 19.