Long Island Serial Killer's disturbing 'planning document' that police found during raid

In 2023, police finally apprehended the man who'd long been dubbed the 'Long Island Serial Killer', following a 30 year investigation.

Investigating officers identified the brutal murderer as 59-year-old Rex Andrew Heuermann, who kidnapped, killed and abandoned the bodies of a stream of local sex workers between 1993 and 2010.

The married father-of-two - who hailed from the nearby neighbourhood of Massapequa - used his 'family man' persona and his successful career as a New York architect as a means of hiding his heinous crimes for three decades.

It wasn't until investigating officers raided his home two years ago after he was listed as a suspect, and stumbled across a 'planning document' on his computer, that the extent of his cruel crimes was revealed.

Heuermann's case has this week been told for the very first time as part of a gruesome new Netflix docu-series, titled Gone Girls: The Long Island Serial Killer.

Shannen Gilbert's disappearance

The investigation began in 2010, when local escort Shannen Gilbert disappeared after meeting with a well-known client in the Oak Beach area.

Minutes into the rendezvous at the known property, she made a frantic telephone call to 911, claiming that someone was 'after her'. The client later told police she'd suddenly gotten spooked and fled from his home into the nearby marshland.

Several days after she went missing, Shannen's mother urged police to conduct a search along Ocean Parkway - a stretch of road between Gilgo Beach, Long Island, and Suffolk County, New York.

Despite investigating officers failing to find the missing sex worker, they were horrified to stumble across a further four bodies.

The 'Gilgo Four'

The skeletal remains of four woman were found wrapped in disintegrating burlap, just a handful of metres apart from one another.

It didn't take long for police to name them as missing escorts Megan Waterman, Melissa Barthelemy, Amber Costello, and Maureen Brainard-Barnes. The group were known to have used Craigslist to meet clients before each disappearing between 2007 and 2010.

Under pressure from the victims' families and Shannen's mother, the police continued their search of the surrounding areas.

Shannen's disappearance alerted police to a multitude of murders (Netflix)

Six other victims

In 2011, six more bodies were found by police between Gilgo Beach and Ocean Parkway.

Two were identified as sex workers Jessica Taylor and Valerie Mack. The body of another woman - who remains unidentified - was also found nearby, alongside that of a toddler.

The final victim was ruled to be a young Asian man, believed by police to be a cross-dresser or transgender due to the nature of the belongings found beside his body.

Shannen's naked body was discovered the same December in the marshland close to where she fled. Despite being found in a similar location and under similar circumstances to the other missing escorts, police ruled her death as an accident - not a homicide in 2014.

The assertion made by Suffolk County Police was just the beginning of a plethora of errors and misjudgements made by the force.

One incident saw Chief of Police, Jimmy Burke, and lead prosecutor, Tom Spota, convicted and jailed for obstruction of justice, after reportedly blocking FBI involvement in the Gilgo Beach cases for several years.

The 'Gilgo Four' (Netflix)

A shocking breakthrough

After a new police commissioner was appointed in 2023, however, a task force including the FBI, carefully went over all the evidence police had compiled in the last 12 years - including witness statements.

One of said statements was given following the identification of Amber Costello's body by a number of her friends.

The group had gone to the police to report a client of her's, who'd acted aggressively during a meet-up in the months prior to her death, describing him as white, around 6'4-6'6, 'ogre-like' and the driver of a Chevrolet Avalanche car.

After a similar vehicle was linked to the areas that the bodies were found, police were able to match the description to a Long Island local - Rex Andrew Heuermann.

Not only did police find that the father-of-two had been adding minutes to a burner phone linked up to the movements of the 'Gilgo Four' victims, but they discovered that his family had been out of town when each of the murders occurred.

After investigators subsequently obtained a pizza box he'd discarded near his NYC office, Heuermann's DNA was linked seven of the bodies.

His hair was also connected to the area that another murdered escort, Sandra Costilla, had been found in 1993.

The police finally boasted a breakthrough in 2023 (Spencer Platt/Getty Images)

Eerie discoveries

Amongst the disturbing possessions found in Heuermann's basement was a hard drive which, despite being wiped of forensic evidence, contained a master 'planning document', upon which he recorded the 'highs and lows' of his crimes

Reporters at the time described the page as a 'roadmap' used by the killer to navigate the ways in which he could 'improve' on each murder.

Other news outlets described Heuermann's work - created in 2000, according to court filings - as a 'manifesto'.

"This planning document crystallises and encapsulates his intent for the commission of these murders," Suffolk County District Attorney Ray Tierney can be seen telling press in the gripping three-part programme.

Heuermann was apprehended in 2023 (James Carbone/Newsday RM via Getty Images)

The document's chilling contents

Amongst other gory details, the document contained a series of columns - one of which was titled 'PROBLEMS', which contained mentions of 'DNA', 'TIRE MARKS', 'BLOOD STAINS', 'FINGERPRINTS', 'WITNESS', 'FOOT/SHOE PRINTS' and 'HAIR AND FIBE'.

A second list - titled 'SUPPLIES' - contained equipment that Heuermann used to commit his murders and cover them up, including 'BOOTIES', 'LIE/ACID', 'ROPE/CORD', 'SAW/CUTTING TOOLS', 'HAIR NETS' and 'BODY WASH/WIPES'.

A third - titled 'DS' (presumably 'dumping site') listed a number of possible locations, including 'MILL RD'.

A different section of the document was titled 'THINGS TO REMEMBER', and included advice like, 'GET SLEEP BEFORE HUNT TOO TIRED CREATES PROBLEMS'. Another read, 'HIT HARDER TOO MANY HIT TO TAKE DOWN'.

A third also reminded Heuermann, 'USE HEVEY ROPE FOR NECK - LIGHT ROPE BROKE UNDER STRESS OF BEING TIGHTENED'.

Other lists were titled the likes of 'PRE-PREP', PREP', 'POST EVENT'.

The house was raided following his arrest (Steve Pfost/Newsday RM via Getty Images)

"This is a document written by somebody who was so determined not to just do it, but do it again and again," New York Times reporter Robert Kolkan explains on the show.

"And as the years go on, he starts to change things up, and get a little bit more organised, a little better at avoiding detection."

Within weeks of his arrest, Heuermann was indicted for the murders of Amber Lynn Costello, Megan Waterman, Melissa Barthelemy, Maureen Brainard-Barnes, Sandra Costilla, Jessica Taylor, and Valerie Mack.

Despite all the evidence against him, his trial hasn't yet taken place.

Gone Girls: The Long Island Serial Killer is now available on Netflix.