Lifetime's 400th original movie, The Long Island Serial Killer: A Mother's Hunt for Justice, premieres Feb. 20

By Jodi Guglielmi
January 22, 2021 10:00 AM
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Never underestimate how far a mother will go for her children.

In PEOPLE's exclusive first look at Lifetime's 400th original movie, The Long Island Serial Killer: A Mother's Hunt for Justice, a woman launches a desperate search to find her daughter after she goes missing following a night out on Long Island, New York.

In the trailer for the film, which is based on a true story, Mari Gilbert (Kim Delaney) becomes alarmed when her daughter Shannan (Katharine Isabelle) fails to return home. Knowing her daughter sometimes works as an escort, Mari immediately fears the worst. 

"Shannan is alive — I have to believe that," she says. 

Credit: Courtesy of Lifetime
Credit: Courtesy of Lifetime

But the search for Shannan leads to an even more unsettling discovery: the bodies of several other missing women. 

Still determined to seek justice for her daughter, Mari becomes frustrated by what she perceives as lack of police action.

"They've been stalling and avoiding," she says of the law enforcement officers handling the case. "I'm beginning to think there's a coverup."

Credit: Courtesy of Lifetime

Though the search for the serial killer is still ongoing, "Mari's passionate dedication to giving her daughter and other forgotten women a voice, and the attention they deserve, has kept the case alive with hopes of a breakthrough soon," the film synopsis reads. 

The movie is produced by Lighthouse Pictures, with Sony Pictures Television distributing. Executive producers include Deborah Norville and Elizabeth Stephen. The script is written by John Pielmeier.

The Gilgo Beach case, dubbed the "Long Island Serial Killer" case, traces back to the discovery of multiple bodies starting in December 2010. Authorities eventually unearthed 10 sets of remains on Gilgo and have said they believe at least four of the deaths — all of women — are linked, raising the specter of one or more serial killers using the area as a dumping ground.

The first body discovered was that of Melissa Barthelemy, when a Suffolk County police officer and his dog came across her remains. Over the next several days, police discovered the bodies of three other young women, all wrapped in burlap and placed within about 500 feet of one another, buried in the marsh on Gilgo Beach.

The remains were later identified as belonging to Amber Costello, Megan Waterman and Maureen Brainard-Barnes. All four women had worked as online escorts and had been missing between 2007 and 2010.

Their remains were uncovered accidentally as police searched for 24-year-old escort Shannan, who went missing after visiting a client, whom she met on Craigslist, in the gated community of Oak Beach on Long Island, and then fleeing the man's home.

Though it was the search for Shannan Gilbert's body that led to the discovery of the others, police don't believe her case was linked and suspected she got lost in the marshland and either died of exposure or accidentally drowned.

The Long Island Serial Killer: A Mother's Hunt for Justice, part of Lifetime's upcoming Ripped from the Headlines slate of true crime movies, premieres Feb. 20 at 8 pm ET.