Will Netflix solve Sister Cathy's murder?
Like all the best murder mysteries, Netflix's The Keepers - the latest slow-burning, gripping series reopening a true-life criminal case - begins with a simple whodunit.
Specifically, who killed Sister Cathy Cesnik? And like the very best in the genre, that question is only the start of something much, much more complicated.
On a late autumn evening in 1969, Cesnik, a popular 26-year-old Catholic nun who taught English at the all-girls Archbishop Keough High School in Baltimore, Maryland, left her apartment to go shopping and never returned.
A search, conducted by the local police force, proved fruitless.
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Two months later, in January 1970, Cesnik's semi-clothed body was discovered at a rubbish dump on the outskirts of the city. She had choke marks around her neck and a blunt trauma - thought to be from a hammer or brick - to the back of her skull.
The killer was never found, nor did the police receive any substantive information: no witnesses, no evidence, no leads. The trail simply went cold.
Almost five decades on, The Keepers - all seven episodes of which were released simultaneously on Netflix on May 19 - seeks to re-evaluate the case by focusing on two of Cesnik's former students, Gemma Hoskins and Abbie Schaub, both now in their sixties, who have spent years piecing together precisely what happened to their favourite teacher.
As Schaub says in the show's trailer, "The story is not the nun's killing. The story is the cover-up of the nun's story".
What unravels across the series is a case far broader and more gruesome than that of this solitary unsolved murder.
In 1994, another former student of Cesnik, Jean Wehner, then approaching 40 and working as a reflexologist, came forward with accusations she had been raped and abused by the school's psychological counsellor, Father Joseph Maskell.
Having suppressed the memories, Wehner recalled the abuse when she saw a photograph of Maskell in 1992.
When another woman, Teresa Lancaster, revealed a similar story, they filed a US$40million lawsuit but ultimately lost when the Catholic church brought a "false memory" expert in to successfully argue the women must have made it up.
However, it was enough to start an investigation into Maskell. Other women started to come forward with similar testimonies that implicated not only Maskell, who died in 2001, but various other clergy members, establishment figures and even the local police force in a murder cover-up.
Wehner and Lancaster both said they had told Sister Cathy about their experiences, Wehner doing so just before the summer holidays in 1969. Cesnik said she would speak to the priests about it. Within months, she was dead. Among many gruesome details linking Maskell to the murder is Wehner's allegation that Maskell led her to see Cesnik's body a week after she was killed - months before the official discovery.
According to a 2015 Huffington Post article about the case, Wehner remembered Maskell whispering in her ear: "You see what happens when you say bad things about people?" as they looked at the nun's corpse.
The Keepers draws on interviews with numerous reporters and police officers, as well as friends and family of those involved, and furthers the now widely-held belief that Cesnik was killed in order to silence her.
As the narrative develops, the sheer scale of the abuse ring and institutional cover-up grows and grows, throwing up dozens of potential suspects, some of whom could still be alive.
There is no knowing where the new attention may now lead. The full truth remains heartbreakingly elusive for Cesnik's former pupils, who have dedicated years to cracking the case. But much of the show's effectiveness comes from its status as a true, open case - the events really occurred and the murder remains unsolved to this day - adding an extra dimension for armchair sleuths watching.
In December 2015, Netflix's Making A Murderer, a documentary series exploring the case of convicted killer Steven Avery, became one of Netflix's most talked about shows, and led to a petition asking for him to be pardoned being delivered to the White House.
In the same year, HBO's The Jinx, another episodic reinvestigation of a historic murder case, led to the show's primary suspect, Robert Durst, being arrested the day before the finale aired.
"The police are a lot more open to the idea of us showing their workings and criime stories are able to be told as compellingly as drama when more emphasis is put on people," says Ralph Lee, deputy chief creative officer and head of factual at Channel 4, which has two true crime series, The Trial and Catching a Killer, beginning in the next three weeks.
It's arguably even more successful in audio. The first series of Serial, an investigative podcast first broadcast in 2014 which looked into the murder of a student in 1999, was downloaded more than 80 million times in a year, while last month, S-Town had more than 10 million global downloads in just four days.
However, last year, critics questioned the ethics of BBC3's Unsolved: The Boy Who Disappeared, a serialised investigation into the 1996 disappearance of Isle of Wight schoolboy Damien Nettles.
It's something The Keepers needn't worry about. Had it been a straight whodunnit, it could have been deemed at best gratuitous.
But by drawing viewers in with the murder, only to kick open the door to a far wider complex web of intrigue, they have created a compelling series which can't be ignored.
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Making a Murderer
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HBO's series centres around Robert Durst, a real estate heir who sought out the filmmaker to help investigate three murders he had long been suspected of carrying out.
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Channel 4's 2015 series investigates the killing of 19-year-old Nicholas Robinson in Bristol the year before, with the story unfolding like a drama.
- The Telegraph, London