Jun
Cracking the Case of the Gilgo Beach Murders: How the Long Island Serial Killer was Caught, and What it Teaches Us About Private Investigators
Beginning in the early 90s, a killer haunted Long Island.
Known as the Long Island Serial Killer, or the Gilgo Beach Killer, the ghost avoided capture for decades, until the discovery of four burlap-wrapped bodies changed everything.
When Rex Heuermann was arrested in 2023, it marked the culmination of years of intense investigative work, where detectives would go to enormous lengths in order to find the right man.
Here at Tracked N’ Solved Investigation Agency, this case was of particular interest to us, not just because of how well-known it was, but because it proved that thorough investigative work, advanced technology, and persistence over the years can close cold cases that previously had seemed hopeless.
Important Facts:
- Rex Heurermann was charged with killing seven women, but it’s suspected he had other victims who have yet to be identified or conclusively linked with Heuermann.
- He is in custody, but has not stood trial yet.
- Heuermann’s first suspected victim was Sandra Costilla, killed in 1993, and his last suspected victim was Amber Lynn Costello, killed in 2010.
- An architect in Long Island, Rex Heuremann, was arrested in 2023 after a lengthy investigation.
- Two of Heuermann’s potential victims were identified in April of 2025, leaving only one unknown victim, “Asian Doe”.
What Were the Gilgo Beach Murders?
For decades, along a long, lonely stretch of road near Gilgo Beach, the remains of multiple women, one child, and one man lay, waiting to be found. Their bodies had been dumped less than 35 feet away from the edge of Ocean Parkway, all within just a few miles of each other.
In December 2010, Office John Mallia and his cadaver dog Blue were searching for Shannan Gilbert near the shoulder of Ocean Parkway when the German Shepard hit on a scent–it was the skeletonized, burlap-wrapped remains of Melissa Barthelemy. That discovery would open the floodgates that would eventually lead to the arrest of the Gilgo Beach killer.
Between 2010 and 2011, 11 sets of remains were found along or near Ocean Parkway. Most of them were women who had offered their services as escorts online, a type of work that left them particularly vulnerable.
Who Were the Victims in the Long Island Serial Killer Case?
A total of eleven sets of remains have been found near Gilgo Beach that are thought to be related to Rex Heuermann, and as of April 2025, all but one of them have been identified. Heuermann has only been charged with seven of the murders, but there’s a chance he could be charged with the deaths of the other four at a later date.
Sandra Costilla
The earliest possible victim of Heuermann, Sandra Costilla, went missing in 1993 and was found a few days later by two hunters. Her body had been dumped in a forested area of North Sea, Long Island, New York.
The 28-year-old woman had come to the United States from Trinidad and Tobago. When she was found, Costilla had been strangled, and her clothes were in tatters.
Costilla’s fingerprints had been taken by police a year earlier when she was arrested for hopping a subway turnstile, and authorities were able to use those fingerprints to identify her after her death.
The Gilgo Four
In December 2010, four bodies would be found within a matter of days, and they would become known as “The Gilgo Four.” These women were Megan Waterman, Melissa Barthelemy, Amber Lynn Costello, and Maureen Brainard-Barnes.
Melissa Barthelemy
The first of the Gilgo Four to be found was 24-year-old Melissa Barthelemy. Melissa was found while authorities were using cadaver dogs to search for Shannan Gilbert, a woman who had gone missing nearby. Like several of Heuermann’s possible victims, Melissa was an escort on Craigslist.
Melissa initially went missing on July 12, 2009. Over the following five weeks, Melissa’s younger sister would receive a series of disturbing calls about Melissa, even telling her that Melissa was dead, and that the caller was watching her rot. The calls were traced, but police weren’t able to identify the caller.
Megan Waterman
Originally from Maine, Megan Waterman was reported missing on June 6, 2010, when she didn’t call to check in on her daughter, whom she had left with family. Waterman was being sex trafficked by her boyfriend and was forced to work as an escort on Craigslist.
She was living in a motel 15 miles from Gilgo Beach when she went missing, and her body was found when police returned to search the site where Melissa Barthelemy’s body had been found a day prior.
Amber Lynn Costello
On September 2, 2010, Amber Lynn Costello was reported missing by her family, but she had likely been missing for longer. Her family wasn’t immediately suspicious when she stopped responding to calls and texts, since they believed she was living in a drug rehabilitation center.
Costello had gone to meet a client who offered her $2500 the night she went missing, and her roommate was able to give police a description of the client’s vehicle–a green Chevrolet Avalanche. This vehicle description would later become a key piece of evidence.
Maureen Brainard-Barnes
Facing eviction, Maureen Brainard-Barnes went to meet a client who contacted her on Craigslist about her escort services. Barnes had tried to pull back from sex work, but found that she didn’t make enough as a telemarketer to pay all her bills.
She was reported missing on July 9, 2007. Like Barthelemy’s sister, a friend of Barnes received a chilling phone call after her disappearance, but when the friend demanded the caller call back on an unblocked number, they ended the call, and she never heard from them again.
Valerie Mack
Outside of the Gilgo Four, six other bodies were found.
Valerie Mack, who also went by Melissa Taylor, went missing in November while doing escort work. Her torso was found on November 19, 2000, in Manorville, New York. Ten years later, in May 2020, her head, right foot, and hands were found in a separate location.
Jessica Taylor
Similar to Valerie Mack, Jessica Taylor’s remains would be found in two separate places. 20-year-old Taylor went missing on July 21, 2003, and her garbage bag-wrapped torso would be found in Manorville.
In March 2011, the rest of Jessica’s remains would be found just a few miles from the remains of the Gilgo Beach Four.
Karen Vergata
Karen Vergata was last seen in February 1996, but she was never reported missing. When her severed legs were found on Fire Island in April of the same year, her identity couldn’t be determined, and she would be dubbed the “Fire Island Jane Doe.”
In April 2011, a second set of remains–Karen’s skull and teeth–were found on Ocean Parkway, seven miles from Gilgo Beach. DNA was recovered from the remains, and Karen was able to be identified via genetic genealogy in 2023.
Tanya Jackson and Tatiana Dykes
Originally known only as “Peaches Doe” and “Baby Doe”, the 26-year-old mother and 2–year–old daughter were found ten miles away from each other. Tanya, like several of the other bodies found, had been dismembered, with her torso being found in Hempstead Lake State Park in 1997, and the second set of remains found in Jones Beach State Park in 2011.
Tatiana was found on April 4, 2011, in Manorville, wrapped in a blanket, only feet from the remains of Valerie Mack.
Tanya and Tatiana were the most recent of Heuermann’s potential victims to be identified in April 2025.
“Asian Doe”
Discovered near the remains of the Gilgo Beach Four, “Asian Doe” was the only male victim associated with the Gilgo Beach murders, and the only set of remains still unidentified. Since the body was found wearing women’s clothing, it’s theorized they may have been a transwoman.
Shannan Gilbert
On May 1, 2010, Shannan Gilbert disappeared from a gated community in Oak Beach while working as an escort. Her disappearance was the most well-documented, and it was the search for Gilbert that would lead to the rest of the Gilgo Beach murder victims being found.
Shannan made a panicked 911 call claiming that someone was after her. She banged on the doors of nearby houses before finally fleeing into the marshes behind the gated community. Shannan’s 911 call was recorded, but she would never be seen alive again.
When her remains were finally found in April 2011, medical examiners determined that she had drowned in the marsh, and while many believe she was another possible victim of Heuermann, her cause of death is listed as “undetermined.”
How Rex Heuermann Was Caught: The Investigation Techniques That Put the Long Island Serial Killer Behind Bars
A number of techniques were used to find Rex Heurermann, many of which are familiar to us at Tracked N’ Solved.
A task force was formed in February 2022 with the sole purpose of investigating the Gilgo Beach murders. With eleven bodies and an enormous amount of evidence to sort through, investigators had to be both thorough and quick in order to piece things together and identify the right suspect.
The Avalanche
Incredibly, one of the most important pieces of evidence had been lingering in the witness statements of one disappearance for years.
After Amber Lynn Costello’s disappearance, her roommate had described to police the huge, hulking man who had hired Costello as an escort. The roommate forced the mystery man to leave when he became belligerent, and he was also able to get a good look at the client’s vehicle–a first-generation Chevrolet Avalanche in an odd, green color.
For some reason, that clue had never been looked into, but the 2022 task force was about to change that.
We know as private investigators that little clues like the description of the truck can make all the difference when solving cases, which is why it’s no surprise the Avalanche would be the first real link to Rex Heuermann.
Police were able to check vehicle registrations from the year Costello disappeared, and found that one matching the exact description had been owned by Heuermann. A little more digging proved that Heuermann, who was heavyset and stood around 6 ‘6, also matched the man Costello’s roommate had described.
Location Tracking and Burner Phones
Now that Heuermann’s truck had put him on the task force’s radar, they dug deeper into his whereabouts during the time the Gilgo Four had disappeared.
Since the Four had gone missing more recently than most of the others, it was easier to track their movements and see who they may have been speaking to before their murders. The women had worked as escorts, and burner phones are commonly used by escorts and clients both to retain anonymity.
Rex Heuermann was found to have a stash of burner phones, and if he had been smart about using them, it might have been a lot harder for authorities to catch him. But Rex was sloppy.
Police were able to recover the cell phone records of the victims, and see the numbers of the burner phones that had called them close to their deaths.
They could also see when those burner phones pinged the same towers as the victim’s phones, confirming that the person using the burner phone was with the victim around the time they were killed.
But where Rex might have really messed up was with his usage of his personal cell phone. Heuermann never used his personal phone to call or contact any of his possible victims, but he made the critical mistake of still carrying the phone with him during his interactions with his victims.
The task force was able to cross-reference the location of Heuermann’s personal phone with the locations of the burner phones and found that the movements matched.
Both phones had likely been in the same place, at the same time–Rex Heuermann’s pockets.
As we mentioned earlier, the killer had taken two of the victim’s phones as trophies and used at least one of them to call Barthelemy’s sister and taunt her about her sister’s death. Whoever was in possession of the phones also used them to check the victim’s voicemail.
Police were able to see what towers the stolen phone had pinged off of when it made that terrible call, and guess whose phone was also in the same area, pinging off the same tower, at the same time?
That’s right–Rex Heuermann’s personal phone.
Incriminating Search Histories
Heuermann didn’t use his burner phones just to contact escorts, either.
Despite being married with children, Rex Heuermann had multiple Tinder profiles. When authorities examined his search history, they found he had searched for disturbing subjects such a torture-related pornography, and images of underage children.
Besides the unsettling searches, Rex also seemed obsessed with himself and the crimes he may have committed. He would search for things related to the ongoing search for the Long Island Serial Killer, such as “why hasn’t the long island serial killer been caught” and “Long Island serial killer phone call.”
Bottles and Pizza Crust
By the time the task force was created in 2022, authorities had found numerous pieces of DNA evidence on the victims. Hairs were found on both the tape wrapped around Megan Waterman’s head and one of the belts used to restrain Maureen Brainard-Barnes.
When the hairs were analyzed, investigators were afraid they had hit a roadblock. DNA proved the hairs belonged to a female, so for a moment, it looked like they had come from the victims. But after the hair from the DNA was cross-referenced with the DNA of the victims, it didn’t match.
So, who did the hair belong to?
Authorities had four strands of women’s hair, all of them strawberry blond, the same shade as Rex Heuermann’s wife’s hair. Heuermann had been under surveillance since he had first become a suspect, and when no one was home, investigators retrieved empty bottles from the garbage cans outside the Heuermann’s Long Island home.
The DNA from the rim of the bottles, Heuermann’s wife’s DNA, was a match for the hair.
The task force was teetering on the edge of linking Rex Heuermann conclusively to the bodies, but even his wife’s hair being at the crime scene wasn’t going to be enough. To have a slam-dunk case, they needed to find Rex’s DNA at the scenes, too.
Luckily, there was one more hair, this one belonging to a male. DNA was extracted from the singular hair, and in order to match it with Heuermann, investigators trailed him undercover until they saw him dispose of his lunch in a trash can on the street.
They rushed to the can and retrieved the box, and by an incredible stroke of luck, there were multiple pizza crusts inside. The crusts were sent to the forensic team, and when the DNA came back, it was a perfect match to the one male hair found on Megan Waterman’s body.
The Aftermath of the Long Island Serial Killer Case
Rex Heuermann was arrested outside of his architecture firm in Midtown Manhattan on July 13, 2023. He was charged with the murder of seven of the eleven victims found near Gilgo Beach, and pleaded not guilty to all of the charges.
As of June 2025, Heuermann is still in custody awaiting trial.
Searches of his home after his arrest revealed other bits of incriminating evidence, such as a Word document that contained an outline for a murder plan and a list of items that would be needed, like ropes, gloves, and tape.
The same document also had a section marked “body prep”, which detailed how to dismember a body and remove identifying factors such as the head and hands. When compared to the condition of Valerie Mack’s remains, the similarities are chilling.
No date has been set for Heuermann’s trial yet, but it will no doubt be watched worldwide once it commences.
How Private Investigators Can Help to Solve Cold Cases
Local police and the FBI worked together to investigate the Gilgo Beach murders and collect enough evidence to arrest Rex Heuermann, but not all cold cases get the same amount of attention from major law enforcement agencies.
When enough time has passed or previous investigations have failed, authorities may close a cold case and cease any efforts to solve it. That’s where private investigators like Tracked N’ Solved come in.
Private investigators can make all the difference in situations such as:
- Child custody disputes.
- Cases that have gone cold due to a lack of police resources and time.
- Families searching for missing persons.
- Legal defense teams that need more evidence for criminal defense.
Consider how the description of Rex Heuermann’s Chevrolet Avalanche was the first piece of evidence to really blow the case open. That little piece of evidence was either missed during the initial investigation into Amber Lynn Costello’s disappearance, or it wasn’t considered important enough to bother with.
Here at Tracked N’ Solved Investigation Agency, we know all too well how important these tiny bits of information can be. Even the most minuscule detail can be the key to solving missing person cases and other cases that may have gone cold.
Contact Tracked N’ Solved Investigation Agency
If you’re looking for a private investigator near Idaho, look no further than Tracked N’ Solved. We are meticulous, detail-oriented, and have the experience to handle even the most difficult cases.
When you need a fresh, unbiased look over a cold case, help dealing with fraud, or assistance tracking down a family member you haven’t spoken to in years, we’re here to help.
Tracked N’ Solved services Idaho, Washington, and Jackson Hole, Wyoming. You can call us at 208-298-8842 or request a free consultation through our website.