True story behind Netflix’s Lost Girls – what really happened to Mari Gilbert

All your questions answered about Netflix's latest harrowing true crime drama

Lost Girls Netflix

Netflix has never been one to shy away from a powerful true crime drama, and their latest film Lost Girls focuses on the suspected victims of the notorious Long Island serial killer.


The series follows Mari Gilbert, who launches her own investigation to find her missing daughter Shannan after the inaction of the police.

Her search leads to the discovery of over a dozen murdered sex workers, and Mari becomes an advocate for murder victims the world would rather forget.

But did this happen the same way in real life? And what happened to Mari Gilbert?

Here’s everything you need to know about this heartbreaking Netflix true crime docudrama.

Who were Shannan and Mari Gilbert?

Shannan Gilbert was working as an escort and disappeared after visiting a client in May 2010. She was last seen running through the town of Oak Beach in the early hours of the morning, banging on the front doors of residences and making a panicked phone call to 911.

Mari Gilbert did indeed become an advocate for her daughter, and later that month the search for Shannan led to the discovery of four bodies on Ocean Parkway in Long Island, suggesting the work of a serial killer.

Netflix Lost Girls
Shannan’s family grieve in Lost Girls

A further six bodies were found off the parkway in March and April 2011, bringing the potential number of victims up to ten. However, none of the remains were found to be that of Shannan.

Shannan’s body was eventually found in a marsh in December 2011. Medical examiners ruled that Shannan accidentally drowned, and concluded “death by misadventure”. Shannan’s family continued to believe she was murdered and arranged an independent autopsy with famed pathologist Dr Michael Baden which suggested she could have been strangled.

Despite the police ruling, Mari Gilbert and her other daughters continued to fight to have the case reopened as a murder investigation and often appeared on television discussing the case.

Is Lost Girls based on a book?

Yes – the series is based on the nonfiction book Lost Girls by Robert Kolker, which recounts the hunt for the Long Island serial killer as well as the lives of five of his suspected victims.

Did they catch the Long Island serial killer?

As of the film’s release in March 2020, the so-called Long Island serial killer is yet to be found or identified.

He is believed to be responsible for the murders of at least ten women over twenty years and gained the name after the bodies were found on the South Shore of Long Island.

However, the police still uphold that Shannan Gilbert’s death is not related to the work of the Long Island serial killer, despite her family’s belief that she was murdered.

What happened to Peter Hackett?

As shown in the film, Dr Peter Hackett called Mari Gilbert telling her he had taken Shannan in and given her medication, only to ring up later and deny meeting Shannan or even calling Mari. However, investigators did find that phone records showed Hackett did indeed ring Mari twice.

Police have revealed that Hackett wasn’t treated as a suspect in the case and that he had a history of inserting himself into major events.

Mari Gilbert filed a wrongful death lawsuit against Hackett, claiming that the drugs Hackett had supposedly administered to her facilitated her death. Hackett denied treating Shannan and the lawsuit was dismissed in 2018.

Peter Hackett now lives in Florida and has refused several interview requests over Shannan’s death.

What happened to Mari Gilbert?

Lost Girls Netflix
Amy Ryan as Mari Gilbert in Lost Girls

Mari Gilbert was stabbed to death by her schizophrenic daughter Sarra in July 2016. Sarra’s mental health struggles are referenced throughout the film, and it is believed Mari tried to intervene after Sarra experienced a psychotic episode after going off her medication.

Sarra was charged with second-degree murder and sentenced to 25 years in jail in August 2017.

Mari’s other daughter Sherre Gilbert continues to fight for justice for Shannan.


Lost Girls is available to stream on Friday 20th March.