- REPORTER: Authorities say they've caught a serial killer in multiple unsolved murders. - REPORTER: Rex Heuermann, a husband and father, is now charged with first-degree murder. - Tonight, a 59-year-old architect, a father of two, is now under arrest, charged tonight with killing three women. - Rex, did you do it? - Police knew ` most likely very quickly ` that this was a serial killer. - There was really a Jack the Ripper on the loose in Long Island. It's a man who calls again and again, who says things like, 'I'm watching your sister's body rot.' We have four victims ` the Gilgo Beach Four. - What's the thinking at this point? I mean, to find this many sets of remains near the same area ` you know you've got something connected here. - This becomes his trophy garden, the place where he can go bask in the memories. - They suddenly start to find more and more bodies. - A fifth victim, a sixth, a seventh, an eighth ` it keeps going and going. Now this is an international news story. - DEBORAH ROBERTS: The mystery at Gilgo Beach really began over a decade ago, with a terrified young woman who went missing in the nearby marsh. Captions were made with the support of NZ On Air. www.able.co.nz Copyright Able 2023 - Kia ora, good evening, and welcome to 20/20. Tonight ` the remarkable story of the Long Island Serial Killer, a case that's still unfolding now, with authorities expecting more deaths to be linked to it. But it's the details of how it all began which are so fascinating. The 911 call and disappearance of 23-year-old Shannan Gilbert sparks a search which fails to find her but eventually turns up bodies of other missing women at Long Island's Gilgo Beach. 20/20's Deborah Roberts begins our story. (CRICKETS CHIRP) - # Can't escape from this sinking feeling. - DISPATCHER: State Police. - ON PHONE: Yeah, there's somebody after me. Somebody's after me. Please. - Are you in Suffolk County or Nassau County? - # Can't run from this growing shadow. - SHANNAN: No! Stop! No! What are you gonna do? Are you gonna kill me? (INDISTINCT MALE VOICES) - # Can't fight # as the darkness follows. (SCREAMING OVER PHONE, BACKGROUND NOISE CRACKLES) # Desperation calls me. # I'm buried deep in the ground. # (Buried deep in the ground.) # (FOREBODING MUSIC) - April 30th 2010 ` Shannan Gilbert is an escort who gets a call to go out to Oak Beach, Long Island. On that night, her client contacts her on Craigslist, and she makes arrangements to meet him at his home. She's got a driver named Michael Pak, who takes her there. - The drill was they would drive around town and wait for a call to come from one of Shannan's Craigslist ads. Then Michael would get a small part of the fee in return for driving her around. That night was a slow night, and she wasn't getting response to her ads until finally she was hired by a guy who lived out in Oak Beach. - He offered two hours for $450, and so since there were not any other appointments, uh, she said, 'OK, let's go.' - ROBERT KOLKER: Oak Beach is really an interesting community. It's very insular. It's on the south shore of Long Island. There's nothing around there. There's no stores, there's no gas stations. There's no anything. - You drive up; there's a gate you have to enter. So Shannan arrives at Oak Beach to her client, Joseph Brewer. She gets out of the SUV, Michael Park waits for her, and she enters a house that she's probably never been to before. - And the clock starts ticking, and Michael Pak stays outside in the car. - DEBORAH ROBERTS: Around 5am, the client, Joseph Brewer, steps out of his home, knocking on the car window. It seems he's having an issue with Shannan and wants Michael to help get her out of his house. - At some point, Shannan gets it into her head that these men are trying to kill her. - Something has really scared her, and she dials 911. - DISPATCHER: State police. - SHANNAN: Yeah, there's somebody after me. - Where are you, ma'am? - I don't know. Can you trace where I am? - No, I can't. - No. No! Stop! No! - BREWER: Come on. Let's go. We'll all go outside. - No. Please. Why? Are you gonna kill me? - PAK: Come on, you're freaking me out. Come on, let's go. - Out in the middle of nowhere? - Let's go back to hom` Let's go back to Manhattan, all right? She freaked out, and she said, um... What'd she say? 'You guys are trying to kill me.' - Shannan sounds like she's fearing for her life. She's so scared that she bolts out of the house, leaving Brewer behind, runs down the road and begins knocking on the door of neighbour Gus Coletti. (SCREAMING OVER PHONE) (URGENT KNOCKING) - I was in shaving at 5 o'clock in the morning, and somebody knocked on the door and was screaming, 'Help me, help me.' - And you can hear him on 911. - GUS: What's the matter? Somebody after you? Huh? - DISPATCHER: Hello? - Are you all right? - SHANNAN: I need help. - Don't get yourself hurt. Where are you going? - Gus Coletti makes his own phone call to 911. - GUS: I live at Oak Beach, in the Association. There's a young girl runnin' around here screamin', and there's some guy trying to follow her. - Shannan then runs down the road to the home of another neighbour and begins banging on that door. (URGENT KNOCKING ON DOOR) - DISPATCHER: What is the location of your emergency? - WOMAN: Some woman is knocking at my door. She says she's in danger. - Do you know her, or no? - No, I don't. I'm not letting her in. - During this whole time that Shannan is running around knocking on doors of Oak Beach, Her driver, Michael Pak, is trying to get her to come back into the car. - At that point, she bolted out and ran down the road that way. He took off after her. That was the last I saw of her. - Eventually, Michael Pak can't find Shannan. Shannan has somehow disappeared. (CRICKETS CHIRP) But at some point, he assumes that she'll get back to New Jersey on her own, and he decides to leave. - Shannan Gilbert's 911 call goes on for about 21 minutes. By the time police arrive, there's no sign of her. She seems to have just vanished into the night. Both Joseph Brewer and Michael Pak say they never threatened Shannan, and police cleared them of any wrongdoing. (SEAGULLS CRY) - Around like 6am, I saw she that she ain't` I saw that she wasn't home, cos she usually gets home around that time. I kept calling the phone non-stop. I figured that she was probably` she probably was in trouble. (SEAGULLS CRY) We went to a police station. They were like, 'Maybe she just ran away.' I was like, 'No, she would not do that.' They didn't take it seriously. - We were calling the police, calling the police ` 'When are you gonna look? When are you gonna search? 'When are you gonna try to find Shannan? 'Do something.' (SEAGULLS CRY) - It took four months before the connection was made between the New Jersey Missing Persons report and Shannan's disappearance in Oak Beach. I think there was definitely some prejudice with regards to taking this case so seriously. We're not talking about a cheerleader. We're not talking about a child here. You know, we're talking about a sex worker. December 11th 2010. (DOG PANTS) There is a K9 officer out with his cadaver dog. (DOG PANTS, SNIFFS) He decides that he's gonna go back to Oak Beach for training purposes, to the place where Shannan last was seen. (DOG SNIFFS) And the dog indicates something. He basically air-scents. - And he started indicatin' to a spot near` off the shoulder of the parkway. At that point, I saw the skeletal` skeletal remains of a body. - The body's that of a petite female that's badly decomposed and wrapped up in camouflaged burlap. It's been dumped in the thick brush near Gilgo Beach, just yards from the highway. - Shannan Gilbert had been struck in her face by her boyfriend; then, as a result, she suffered an injury that` the repair required a titanium plate to be put into her jaw. - The body that they found was severely decomposed, had been out in the elements for an extended period of time, but this titanium plate would always be there. - The lack of that titanium plate in the human remains, I think, that helped determine that it was not Shannan Gilbert more rapidly than may otherwise have been the case. - ROBERTS: So if this isn't Shannan Gilbert, who is it? - That body ` we learned later that's Melissa Barthelemy. Melissa Barthelemy was 24 years old. She had disappeared in the summer of 2009. That's a year and a half when... the police don't have any success finding her. - There were similarities between Melissa and Shannan. Both of them were about the same age, they were both petite, and they worked in the sex industry. - Melissa had just gotten out from under the thumb of a boyfriend who had, in effect, become her pimp, and she was living independently and, um, trying to support herself, and Craigslist offered a way for her to be her own boss. You could just post a picture with your phone number; somebody would call you. - It was believed that she had gotten a call and she was gonna go out to visit a client in Long Island. - A few days went by, and, you know, no phone calls from her, and it... just wasn't like her. - I actually started calling hospitals, jails. Nobody knew where Melissa Barthelemy was. It was like she vanished. (PHONE RINGS) - Soon after Melissa disappears, her 15-year-old sister, Amanda, starts to receive a number of phone calls around dinnertime. (PHONE RINGS) Amanda's phone rings, and she looks at it, and the caller ID is coming from Melissa's phone. - Amanda's like, 'Wow. Oh my God ` it's Melissa.' And she answers the phone, and there's a guy on the other end. And she's like, 'Where's my sister? Who is this?' - The person said, 'I'm watching your sister rot.' - Final call was, uh` he actually said what he did to her. He actually told Amanda that he killed her sister ` 'You should've seen her face.' - Five months later, back at Gilgo Beach, investigators are fanning out into the marsh near Ocean Parkway, searching for more clues, but nobody is prepared for what the landscape is about to reveal. (OMINOUS MUSIC) - They found another body and another body... and then another one. - Yes ` the astonishing death toll being revealed as more bodies are found in the sands at Gilgo Beach. (DRAMATIC NEWS STING) (DRAMATIC NEWS STING) You're with 20/20. Welcome back. Following the disappearance of Shannan Gilbert at Gilgo Beach, police have found and identified the remains of a different young woman. Then the search is intensified, and to the shock of many, more bodies are found in a remote part of New York's Long Island area. They're eventually identified as four women with many similarities. (DOG BARKS) - After first finding the body of Melissa Barthelemy, police spent the next two days searching the area. This area is totally desolate. It's the open face of the ocean. There's nothin' there. - REPORTER: Late this morning, Suffolk County Police announced details of a startling series of finds. - REPORTER: The decomposed bodies were found off a roadway along Gilgo Beach yesterday, possibly dumped out of a car. - DEBORAH ROBERTS: Police find three women, all in their 20s, and they'll later identify them as Amber Costello, Maureen Brainard-Barnes and Megan Waterman. - ROBERT KOLKER: They're found together. They are placed together, essentially, one by one, a short distance away from each other, each of them fully intact. They found three bound with what turns out to be burlap. - The way the` the bodies were handled, um, definitely suggests somebody who knows the area, and once he has succeeded in placing a body in this location, this becomes his` his trophy garden, his... the place where he can go and bask in the memories of killing these women. - JOSHUA ZEMAN: These four women, who we now know as the Gilgo Beach Four, they all fit an MO ` they're all petite, like five feet; and they had all been operating in the tristate area as sex workers. - ROBERTS: Maureen Brainard-Barnes was the first of the Gilgo Four to go missing. - KRISTIN THORNE: Maureen Brainard-Barnes was 25 years old when she disappeared July 9th of 2007. Two weeks after Maureen disappears, her friend Sarah gets a phone call from a man saying that he knows where Maureen is. - He goes, 'Do you know Marie?' (CHUCKLES SHORTLY) And Marie was her escort name. You know, I'm like, 'Well,' you know, 'what does she look like?' He said, 'She's short,' and I said, 'Yeah.' 'She's got dark brown hair that's` yeah, to her shoulders.' 'Uh-huh.' 'And on her right arm, she has a tattoo that says Nicole or something.' 'Well, that is her. That's`' You know, 'That's my friend.' He's like, 'She's not missing. 'Well, I just saw her at a whorehouse in Queens.' (OMINOUS MUSIC) 'Wow. Yeah? That doesn't sound right to me.' - When Sarah hears 'whorehouse' ` it's not a term that's thrown around these days. You imagine that whoever was making this call, you know, is someone a little out of the` out of touch with the times. - And` You know, and I'm like, 'Can you call me back unblocked? 'Because I need to tell the cops and her family this 'so that they're not worried anymore.' And he's like, 'Yeah, yeah, sure, sure.' Never called me back. - The idea that this man would call a victim's friend and taunt them like this is really sickening. - REPORTER: Six weeks after the grisly discoveries of four human skeletons on this deserted barrier island, those bodies have names and faces. (INDISTINCT CHATTER) - OK. One of the bodies that we found on December 13th has been positively identified as Megan Waterman. - The last place she had been seen was leaving the Hauppauge- Long Island Holiday Inn. She left. She left her cell phone. And that was the last time anybody ever saw her. - A video camera captures her leaving the lobby of the hotel. It seems as if she's been told to walk a short distance from the hotel to where she might get picked up by someone who doesn't want to be seen. And you could say, you know, that's the work of a clever serial killer, but you could also say that's the work of a John who doesn't wanna be noticed by anybody at a hotel. - ROBERTS: The last of the Gilgo Four for to disappear is Amber Costello. - Amber Costello disappeared just three months after Megan Waterman, in September of 2010. - Amber had become dependent upon drugs, and she had been living with her boyfriend and a guy named Dave Schaller. - Amber ` you know, she was` she was a sweetheart. If she had different... you know, different channels, she would've been able to do something a lot better with her life. - Amber and Dave Schaller, they had a sort of setup that when a man would come see Amber, Dave would come into the house and pretend to be the angry boyfriend. The client would get so upset that this boyfriend had come in that the client would just leave and Amber would get to keep the money. - One night they try to run this scam and Dave gets a good look at the guy, and he's unusual because he's so tall. He later describes him as 'an ogre'. When he runs away, he gets into an unusual car, a Chevy Avalanche. - Later on that night, Amber got a text from this male client saying, 'That wasn't very nice.' He demanded a credit. - When she went missing... She called me earlier that day, and she said, 'This guy keeps calling me. 'He won't leave me alone.' - Dave Schaller basically told authorities, 'We had been running this ruse. We ran it on a guy, 'and then Amber disappeared.' - He remembered this interaction, and he remembered the Chevy Avalanche. So something in his mind knew at that time that something was off. By spring of 2011, I think law enforcement had realised they have a big problem on their hands and that they should probably go search the entire area. - They start sending legions of officers up and down Ocean Parkway. - Police officers, firefighters, emergency workers. People, you know, descended from cranes to go into deep bramble. - The FBI was asked in to help with the technical part of this investigation. Uh, we help identify where bodies are located. - ZEMAN: They suddenly start to find more and more bodies. - A fifth victim, a sixth, a seventh, an eighth ` it keeps going and going. - REPORTER: Law enforcement officers have been combing the tall grass here. - I was right there when the K9 officer realised that what she had found was a child, and I think it was a gut punch to all of us. - ROBERTS: Unbelievably, there are now 10 sets of human remains. - Are they dealing with one killer, two killers? How many killers could have been involved in these murders? - The toll's becoming sickening, and there are so many questions still to answer. (DRAMATIC NEWS STING) (DRAMATIC NEWS STING) Welcome back to 20/20 and tonight's story on the Long Island Serial Killer. As we resume, a ghastly death toll has been growing, with numerous corpses recovered and specialist teams continuing to search. But Shannan Gilbert, the 23-year-old whose frantic call to police sparked the initial search in the area ` she is still missing, and her family is frustrated with a lack of action. - REPORTER: Thursday, April 14th 2011. - The manhunt for a serial killer underway right now on New York's Long Island, the FBI preparing high-resolution cameras to fly over the area where police found human remains. - Despite Suffolk County Police finding all of these bodies between December of 2010 and April of 2011, they still did not find Shannan Gilbert. - This is not a television show where everything is solved in an hour. - I am so very tired of him saying that. I'm not gonna let this end until I find my daughter. - So, not only did we want to find Shannan Gilbert to get closer to our families; we just felt compelled to find Shannan Gilbert. So I suggested we go back into the Gilgo Beach area. This is the area adjacent to where she was last seen. - It's a bunch of waterways, almost, and they're, like` sometimes they're six feet deep, depending on the water situation. - The only way to find her body is to use these special vehicles that will allow detectives to go through the marsh but not get stuck in these deep canals. - STUART CAMERON: We were able to drive that around and much more rapidly search the area. So, during the search, again, John Mallia finds a pair of shoes, a pair of pants and a pocketbook. - With identification in the pocketbook belonging to Shannan Gilbert, we believe that this is her pocketbook. (UNSETTLING MUSIC) - CAMERON: Then, early in the morning on December 13th, we found a set of human remains. - REPORTER: After a year and a half, police on Long Island believe they have found Shannan Gilbert, a prostitute who vanished after parting with a client she met on Craigslist. - The police believe that my sister was either so intoxicated or so strung out on drugs that she just ran into the marsh, got stuck and just expired. - Lookin' at the terrain ` uh, it's very easy to get engulfed with water, muck and, uh, you know, fall down and not be able to get outta there. - Police believe that Shannan may have drowned or died of exposure somehow in the marsh. Her death doesn't follow the pattern of the Gilgo Four ` she was found in a different area; she wasn't wrapped in burlap. But despite the authorities' conclusion, Shannan's family's convinced she was murdered by the same killer. - Shannan's death was not an accident. Her death was not an accident. (BROODING MUSIC) - When all the years went by and absolutely nothing was being done about this, I thought that... they were never going to ever catch this man. - The families had been outraged that this case had not only gone cold, that it was in a deep freeze, that this case was nowhere. - So, I arrived in Suffolk in April of '18. The thought was, 'All right, 'we really need to kind of reinvigorate this investigation.' - Thank you for joining us. - She calls a press conference in January 2020. - Today, we are releasing the first piece of new information... - A belt that had been tied around one of the victims, Maureen Brainer-Barnes. - A black leather belt embossed with the letters 'HM' or 'WH' was recovered during the initial stages of this investigation. - And then, two years after the belt tip is released, the case is invigorated yet again. How many agencies were involved in this? - We had the state police, we had the sheriffs, we had the FBI, and we had the Suffolk County District Attorney's Office all working together. - We had our first task force meeting February 1st of 2022. - Then, just six weeks later, the taskforce has a suspect ` for the first time in 13 years. - Tonight ` breaking news. The stunning arrest ` authorities say they've caught a serial killer in multiple unsolved murders. - REPORTER: Rex Heuermann, a husband and father, is now charged with the deaths of three of the victims found on the barrier beach off Long Island's south shore. - Heuermann, a 59-year-old architect, is taken into custody just blocks away from his office in midtown Manhattan. - KRISTIN THORNE: He certainly doesn't try to run. We can't hear anything. It's very calm. - It was as much of a surprise to me as it was to everybody else that was watching television that morning. - I had no idea who he was or anything about him. - Rex, did you do it? - But everyone's about to learn about Rex Heuermann. First off, while the arrest was in Manhattan, he's actually a commuter. He lives in a small town on Long Island, Massapequa Park, which isn't far from where the four bodies were found. And secondly, he's a really big guy. - Rex Heuermann is... a very large individual. If you look at his perp walk, he is like a head above any of the police officers who are leading him. - REPORTER: The 59-year-old architect and married father of two now charged with killing three women. - Heuermann's charged with both first- and second-degree murder for the deaths of Melissa Bartholomew, Megan Waterman and Amber Lynn Costello. He pleads not guilty. - And as for the fourth victim, Maureen Brainard-Barnes, Heuermann is the prime suspect, according to police, but he's not been charged in her death. - There is a lot of intrigue around Rex Heuermann and who he is, but the big question is ` how did police break the case? - So, there was not a lot of forensic value at the crime scenes. What we did have is we did have five, uh, hairs. There was one hair in particular that was stuck between the tape that was used to bind Ms Waterman. - Using advanced DNA technology, investigators say they determined that the hair found on Megan Waterman belonged to a Caucasian male. - So we had the hairs, and then we also had the great work done by the FBI and their cell phone experts, who had looked at some of the burner phones that the killer used as well as some of the victim phones and had established areas of interest. - We had cell site hits in two areas ` in Massapequa Park and also in Midtown Manhattan. There was, like, a little bit of what's` we call it a box, where our potential suspect was making these phone calls to our sex workers. - RAY TIERNEY: And we essentially went from, you know, over 1000 homes to under 200 homes, and we were able to pinpoint the Manhattan location to a very specific area in Manhattan. (TRAIN RATTLES OVER TRACKS, BELL DINGS) - It really helped us narrow in to, uh, saying that whoever is our suspect probably has a residence over in Massapequa Park and has some type of work in Midtown Manhattan. - By 2022, even though authorities have narrowed down their search area and they've got a suspect profile, detectives still don't have that critical piece of evidence that points toward a name. But it turns out the biggest tip has been hiding in the case files for years. - It was a New York State Police investigator who... took another look at the fact that there was this identification of a vehicle that Amber Lynn Costello had last been seen leaving in. - The roommate is the one who gave us the information that she had a customer who drove a green Avalanche who is 6'6", 275lb, fuzzy hair. - That information came in at the beginning of the investigation, uh, in 2010, 2011, uh, along with what was really thousands of tips. And unfortunately, it gets` it gets lost and buried. - And once we brought that state police investigator who had access to a different database and was able to track it down to that Massapequa Park box that we've identified ` um, really put us in a place where Rex Heuermann was our guy. - So now that they have a name, the taskforce, of course, escalates the investigation. They begin closely surveilling Heuermann and issuing more than 300 subpoenas over the next 16 months. - RAY TIERNEY: What you're looking for is you're looking for additional information, whether it's financial records, phone records, forensic information... - The bail document paints a really disturbing picture. Law enforcement says they were able to review the suspect's Google history. They say they found searches related to violent pornography, to child pornography, and they say they also found searches related to the Gilgo investigation itself. - In a 14-month period, he searched the Gilgo investigation over 200 times. - They started putting surveillance on Rex Heuermann, and they would follow him, but they needed DNA evidence. You had a crime that was so many years old, and they had nothing to tie anybody to the location. - They needed something that Rex Heuermann would throw out that would have his DNA on it. They were outside his office, and a detective saw him come out and throw out a pizza box. - REPORTER: In the end, prosecutors say, the smoking gun was a pizza crust. Police dug through Heuermann's trash, matching DNA from a partially eaten slice to previously unidentified hairs found on three of the Gilgo victims. - According to law enforcement, Rex Heuermann has these alias email accounts. We know that he has these burner phones, according to police. Police say up to this year, Heuermann was still attempting to contact sex workers. (TENSE MUSIC) - We weren't planning on doing the takedown of Rick Heuermann that day, but we got concerned about information possibly getting out due to the fact that we're going through a grand jury and trying to get him pre-indicted. - So he's walking out, unsuspecting, and the agents come up to him. What's` What's his reaction? - It wasn't any struggle or any fight. He goes, 'What am I being arrested for?' We informed him what he's being placed under arrest. - So, while that was happening in Manhattan, there was a team going out to the house in Massapequa Park. - Police have now descended on the Heuermann property, and the house and this Long Island suburb are completely upended. - And then we did a search warrant at his residence and recovered close to 300 firearms. - Every square inch of the house was removed. - Investigators spent much of the day searching Heuermann's home, checking to see if any mementos are trophies. - If there's any evidence inside that house, we're gonna collect it, and we're going to use it against him to make sure we hold him accountable. - So police are going after their suspect. But how many deaths will they be able to link him to? (DRAMATIC NEWS STING) (DRAMATIC NEWS STING) Welcome back to 20/20. An arrest has been made over the deaths of the so-called Gilgo Beach Four, four young women whose bodies were found in the Long Island area. There are still other, unidentified victims found nearby, but those remains that are known have been there for some time and can only offer limited forensic and physical evidence for investigators, so now police have to build the case against their suspect by delving into his life. - KRISTIN THORNE: Rex Heuermann is now in jail. - Rex, did you do it? - He's been charged with first-degree murder, and now police have an opportunity to dig up even more evidence. (TENSE MUSIC) They go into his house; they rip it apart looking for any piece of evidence to potentially tie him to the murder victims. - Given the type of case it was, you wanted to get all types of evidence, from large tangible pieces of evidence as well as microscopic evidence, forensic evidence ` hair, fibres, blood, DNA, what have you. - RODNEY HARRISON: Recovered close to 300 firearms. - The defendant fancied himself a collector. - According to police, Rex Heuermann seems to be particularly skilled at leading a double life. He's been a long-standing husband and father, and now his family's life has been completely upended. - DEBORAH ROBERTS: He's been married to Asa Ellerup since 1996. Has she given you any indication about whether she was happy in her marriage? - She has. I think they were` You know, any marriage, after that time period, you hit certain lulls. - ROBERTS: The couple shared a daughter, Victoria, and raised Asa's son, Christopher. They were all living in the same home Heuermann grew up in. And the question on everyone's mind is ` what did the family think? - The public has convicted their father. I think they're looking to reserve judgement until they actually can see and hear what actual physical evidence there may or not be. - Victoria, Christopher and Asa are already distancing themselves from Rex Heuermann. - Asa Ellerup has filed for divorce from Rex Heuermann. She filed very quickly. - Many people would ask how you could be married to somebody for 20-plus years and not know something. - She hasn't expressed any of that. Police Commissioner has come out and said she's not a suspect or accomplice, and they've actually said she was out of the jurisdiction when these alleged homicides took place. Like I said, if they happened, it was a complete double life that her husband lived. - New developments in the Gilgo Beach murders ` the investigation expanding. - To include Heuermann's property ` both in South Carolina and Las Vegas, Nevada. Remember that key piece of evidence for investigators, that green Chevy Avalanche? - REPORTER: Police seizing this older-model Chevrolet Avalanche at Heuermann's vacant lots in Chester County, South Carolina ` the same kind of vehicle that an eyewitness told police he saw before one of the victims disappeared. - Police in these areas are asking, 'Are there more buried bodies to be found?' And so they're now analysing all of their cold cases. - ROBERTS: What about all those other bodies also discovered in the marsh? (CRICKETS CHIRP) - REPORTER: Authorities say they have likely found the woman's remains ` 24-year-old Shannan Gilbert. - ROBERTS: It was Shannan Gilbert's disappearance that led police to the discovery of the women now known as the Gilgo Four. But more than a decade later, her family still has big questions about how she died. - The medical examiner in Shannan Gilbert's case ruled that her cause of death was inconclusive ` undetermined. - It does sound like the most outrageous coincidence. After all, it was the search for Shannan Gilbert that led to the first of those gruesome discoveries. - My condolences go out to the family. But it's an unfortunate` But right now, we... we believe it was just a horrible accident. - You stand by the investigators' conclusion that she was not connected to this case? - I do. (UNEASY MUSIC) - DISPATCHER: Hello? - SHANNAN: Hello. - Do you need the police? - ROBERTS: Remember, before she ends up in that marsh, she calls 911 for help. - SHANNAN: Somebody's after me. - Somebody is harassing you? - After me. - Who? - No. Stop it. Please. Stop it. Please! (SCREAMS) - She was definitely in trouble. She wouldn't act like that just for no reason. Yeah, she was in trouble. - There's security cameras out here, but they never got the surveillance video tape from them. You never`? - The police never came for the security cameras for many days, and in the meantime, they got erased. - According to court documents, those security camera tapes were routinely recorded over. - The police suggest that Shannan was hysterical, that she ran into the marsh because she could see on the other side of the marsh the lights of the highway. - I'm told that the marsh can actually be more like a lake when it's holding a lot of water, so, you know, the water would have been very cold; she could've become hypothermic going in there. - Her pants and her purse were found at some distance from where police found her body. Why would she be so far from her belongings? - I believe that Shannan was murdered. - The attorney for Shannan Gilbert's family hires a forensic pathologist to do an independent autopsy. - TIMOTHY BOLGER: His name is Dr Michael Baden. He reports that Shannan's death was consistent with homicide and inconsistent with natural causes. - They hired a pathologist who concluded the opposite of what investigators had said. - Mm-hm. - Does that change your view, potentially? - Not at all. I'm not gonna get into a debate with John Ray. My investigators have ruled this investigation as a horrible accident. - ROBERTS: To this day, the family still doesn't know why Shannan was so agitated and why she wound up in the marsh. - ROBERT KOLKER: We may never really know what happened to Shannan. (SOMBRE MUSIC) - We came to this place at this moment in Shannan's yet-unfinished calamity to comfort her family. - Mari Gilbert died in 2016, never fully accepting the police version of what happened to her daughter or knowing how the case of the Gilgo Beach murders would be resolved, but her fierce fight in the search for her daughter may very well lead to justice for other families. - Mari had a growing devotion to her daughter. I think there's a core love for her daughter she always had. (SOMBRE MUSIC) And like any mother, sh... she cared. She saw her daughter as a hero in the sense that her life and her sad ending at least had a value to it that went beyond herself. - This arrest would not have happened in July of this year if it hadn't been for Shannan Gilbert. - It was because of her that all of this evil was uncovered. She is the unintentional hero of this story, and that's what I hope people remember about her. - Authorities are building their case against Rex Heuermann and tell us they're still combing through the evidence. Right now, we're talking about these three` now maybe four victims. What about the others, then? - Yes ` when we come back, the fight for justice for the rest of the victims at Gilgo Beach. (DRAMATIC NEWS STING) (DRAMATIC NEWS STING) Thanks for watching 20/20 and tonight's story on the Long Island Serial Killer. Rex Heuermann's been charged with the murders of three of the young women found on Gilgo Beach, and police are working on linking him to a fourth. But the search also found multiple other human remains, and there are still so many questions about them. (BROODING MUSIC) - JOSH MARGOLIN: As of September 2023, Rex Heuermann has pleaded not guilty to charges that he murdered three women ` Melissa Barthelemy, Megan Waterman and Amber Lynn Costello. - Heuermann has not been charged in the death of Maureen Brainard-Barnes because there just is not enough evidence right now that prosecutors have, but they've made it clear that they expect that to come soon. - I believe that the lab work, once it comes back, is going to attach that fourth unfortunate body that was discovered on Ocean Parkway to Rex Heuermann. - But remember, in addition to the Gilgo Four, six other bodies were discovered in the same area ` four more women, a man and a toddler. - What about the others, then? How much progress are you able to make in those cases at this stage? - We still have some work to do regarding getting these individuals identified. That's why this taskforce is gonna stay in place. We'll continue to investigate the other bodies that were discovered on Ocean Parkway. - Rex Heuermann's attorney declined to comment when asked if his client was involved in the deaths of Maureen Brainard-Barnes or others found along Ocean Parkway. He tells ABC News in part, quote... (DISTANT BIRDSONG, WIND BUFFETS) (SOMBRE MUSIC) - I think the Gilgo Four case helped put a face on victims in a way that few serial killer cases do. - These women were mothers, sisters, friends, and we need to remember that they are real people with real memories, with real childhoods. - You could meet Megan the first time and you'd fall right in love with her. - Melissa was just beautiful all the way around. - Amber was just full of love and life. She just loved life. Always there for her loved ones. Would move heaven and earth to help them. - Maureen's personality was very bubbly. She literally and figuratively would give anyone the shirt off her back. I love you. I miss you, Maureen. (SOMBRE MUSIC CONTINUES) - Me and the other victims' families, we're one big family now. Not by blood. We were bought... as a family by tragedy. - Ready? Let's go! (SOMBRE MUSIC CONTINUES) - ROBERT KOLKER: People have tried to sort of shed light on the fact that the people in this case were vulnerable long before they were killed, that we need to do better to shine a light on people who are vulnerable. - Rex Heuermann's case has not yet gone to trial; his attorneys are requesting more time to review evidence. We'll, of course, keep you updated. But that's our show for tonight. Thank you so much for joining us this Monday. Until next week, kia ora; nga mihi. ('20/20' THEME) Captions by Maeve Kelly. Captions were made with the support of NZ On Air.