A Netflix documentary series has unravelled the unsolved killing of a nun in 1969, with hopes that victims and witnesses of sexual abuse come forward to testify.

The Keepers, a seven-part series, released late this month by Netflix explores the cold case murder of Sister Cathy Cesnik who taught at Archbishop Keough High School.

The TV programme poses the theory that she was killed as she was about to turn whistleblower on a paedophile network organised by two priests.

The 26-year-old nun's car was found abandoned a day after she vanished while out on a shopping trip.

Her battered and mutilated body was found on a remote hillside eight weeks later. Police believe the cause of death was blunt-force trauma. The killer was never caught.

Paedophile network

The Netflix true-crime series focuses on allegations of sexual abuse by Father Joseph Maskell and Father Neil Magnus at the Baltimore Catholic school. There are detailed interviews with former pupils who say they were victims of group rapes. Police officers are also alleged to have taken part.

The priests are said to have chosen their victims when they heard their confessions, selecting vulnerable children who were being abused at home.

One former pupil of the school, Jean Hargadon Wehner, alleged she was raped at 14, and told it would “cleanse her soul”.

On film, Wehner says Sister Cathy Cesnik was the only teacher who had tried to stop the sexual abuse.

Wehner tells of how Father Maskell brought her to see Cesnik's corpse, before it was discovered by police, and warned her: “You see what happens when you say bad things about people?”

Detectives involved in the 1970 investigation told The Baltimore Sun that their efforts were impeded due to lack of cooperation from the Archdiocese Of Baltimore.

Catholic cover up?

After a visit to the police commissioner by archdiocesan representatives, detectives said they were forced to curtail the questioning of a priest over Cesnik's death. One official claimed he was ordered to destroy investigative documents because of church sensitivity.

Spokesman for the archdiocese, William Blaul, denied that any interference took place.

Father Maskell was chaplain to the Baltimore county police, the Maryland state police and also the local National Guard. He had close connections with the city's Catholic network.

In 1995, Maskell was defrocked after police discovered documents which included psychological profiles of his victims. He died in 2001 without having been charged.

More than 30 women revealed that they had been sexually abused at Archbishop Keough High School. Settlements of around $50,000 were paid out to 13 former students of the school by the archdiocese of Baltimore.

The documentary also suggests that the murder of Joyce Malecki, an office worker with links to the parish, could have connections with Cesnik's killing.

The FBI said in a statement: “The Keepers is rightly bringing attention to the senseless and unsolved murders of Sister Cathy Cesnik and Joyce Malecki.”