Gilgo Beach killings: Suspect Rex Heuermann had a 'manifesto' to plan and carry out killings, prosecutors said

Alleged Gilgo Beach serial killer Rex A. Heuermann maintained a “planning document” between 2000 and 2002 that investigators believe allowed him to methodically plan out his kills and prepare to evade law enforcement, prosecutors revealed at his arraignment Thursday in two previously uncharged killings.

“This is a manifesto that methodically outlines how to carry out the selection and murders,” Assistant District Attorney Nicholas Santomartino said at Heuermann's arraignment on the new charges on Thursday morning.

Hair found decades ago at the wooded crime scenes where the remains of Sandra Costilla and Jessica Taylor were found also provided the Gilgo Beach Task Force with a DNA link to charge Heuermann, 60, of Massapequa Park, in their killings, Suffolk County District Attorney Ray Tierney said.

Newsday first reported the new indictment on Monday. Heuermann had previously been indicted on multiple murder charges in connection with the killings of four women whose remains were found near Gilgo Beach in 2010.

The “manifesto,” discovered when a laptop seized under a July 2023 search warrant on his home was analyzed March 7, gave those same investigators the “blueprint” to understand just how Heuermann operated, the prosecutor added.

“We allege that this document [shows] the defendant’s intent of committing the charged crimes,” Tierney said shortly after the Manhattan architect pleaded not guilty in front of State Supreme Court Justice Timothy Mazzei to a superseding indictment charging him with six  killings. “His intent was specifically to locate these victims, to hunt them down, to bring them under his control and to kill them.”

The document, which prosecutors said was deleted but recovered using forensic software, listed “problems” a killer might face like DNA, witnesses, blood stains and material evidence. It also included an outline of supplies that might be used by someone looking to kill — rope, hair nets, acid — and references apparent dump sites and possible future targets. Tierney said Heuermann also studied the book that inspired the Netflix series “Mindhunter,” written by famed FBI serial killer profiler John Douglas, to improve as a killer.

Prosecutors, in a bail letter released Thursday, wrote in part, “Based on the Gilgo Homicide Task Force’s training and experience, the members believe 'PROBLEMS' to be a guide on issues to avoid apprehension, 'SUPPLIES' to be a reference to what supplies are needed to carry out the serial murders, to avoid apprehension, and to avoid leaving behind DNA evidence. The 'DS' heading appears to be an acronym for 'dump site,' which is corroborated by, inter alia, the discoveries of Valerie Mack and Jessica Taylor at two separate 'dump sites,' i.e., the vicinity of Mill Road and Ocean Parkway. Under that same heading is a note regarding 'dumpster sites,' which the Task Force members believe is a reference to how Heuermann disposed of physical evidence in the manner described. … 'TRG' appears to be a reference to target or victim (see embedded image below). It is important to note that the known victims thus far are all petite women, which is consistent with the 'SMALL IS GOOD' entry in the document, lending further support to the aforementioned conclusion that 'TRG' refers to victims or 'targets.' ”

Tierney said the investigation into additional killings possibly committed by Heuermann is ongoing.

The two new counts of second-degree murder expand the charged Heuermann killings to 1993, when Costilla was found badly beaten in a wooded preserve off Old Fish Cove Road in North Sea. That location also moves the investigation more than 40 miles from Ocean Parkway to Southampton Town. Those facts, combined with the information Taylor was dismembered unlike four previously charged victims, dramatically reshapes the case, which already included 10 potential victims at Gilgo Beach, Tierney said.

“All those cases, every case, every person who was tragically murdered in Suffolk County, they are in play,” the district attorney said.

One piece of evidence prosecutors said links Heuermann to the Taylor death is motor vehicle records showing he bought a Chevy Avalanche just four months before she was killed only to trade it in days after her remains were discovered in Manorville, Tierney said.

A witness told authorities that on July 25, 2003, at about 10:30 p.m., they spotted a dark-colored Chevrolet pickup truck backed into the same wooded area along Halsey Manor Road in Manorville where Taylor's body was later found, the bail letter said.

Taylor had been decapitated and dismembered at her arms below her elbows, and there was an “obliteration” of her tattoo. Additional remains were found off Ocean Parkway in 2011.

“Investigators believe the mutilation of the victim's tattoo, decapitation of her head and dismemberment of Ms. Taylor's arms, were acts perpetrated by Rex A. Heuermann to … inhibit the identification of the victim via facial recognition, fingerprints and/or tattoo identification,” the bail letter said.

Authorities also noted in the bail letter that Heuermann accessed a Newsday article about the discovery of Taylor's remains on July 28, 2003, online activity that was later deleted. Heuermann then conducted an internet search for a new Chevrolet Avalanche, with a blue exterior and white interior, despite his 2002 Avalanche being just over a year old, the bail letter said, adding that there was an attempt to delete the vehicle search as well.

“Notably, this activity occurred just days after Ms. Taylor was discovered and just days after witnesses observed a vehicle matching the physical description of Heuermann’s leaving the scene,” the bail letter said.

Heuermann was home alone when both Taylor and Costilla were killed, Tierney said, with his wife and children visiting a Vermont resort when investigators believe he was with Taylor, and when a former partner and his mother moved out of the house shortly before Costilla met her demise.

Tierney said it is not known how Heuermann knew Costilla, who unlike each of the other five women alleged to have been killed by him, is not known to have been a sex worker.

The remains of Costilla, a native of Trinidad and Tobago whose family members were not present in the courtroom Thursday, were found by a pair of hunters on Nov. 20, 1993. She was “lying on her back with her arms outstretched over her head with her uncovered legs spread apart,” a bail letter provided by the district attorney’s office said. Her shirt had been pulled over her torso and head, exposing her breasts. Costilla's remains also had 35 “sharp force injuries, including to her face, torso, breasts, left thigh and vaginal area,” prosecutors said.

Three hairs were found with her remains, including one on her right arm and two others from a “tape-lift” of two shorts that were above her head, the letter said.

What prosecutors call Heuermann's 'manifesto'

Investigators said they found this "manifesto" on how to kill and avoid detection on a hard drive in the basement of Heuermann's house during a search after his arrest.

DNA analysis found that one of the hairs could not be excluded as having belonged to Heuermann, despite 99.96% of North America's population being excluded as a source for the hair, the bail letter said, which also noted another lab had reached a similar conclusion.

Another hair found on Costilla's body is a likely match to a woman who lived with Heuermann before Costilla's disappearance, the bail letter said. While Tierney declined to name that woman, court records show Heuermann was divorced from his first wife, Elizabeth Heuermann, in May 1994.

“Accordingly, the murders of all four charged victims, and now the murders of Ms. Taylor and Ms. Costilla, occurred at times when Defendant Heuermann would have had unfettered time to execute his plans for each victim without any fear that his family or others residing at [his residence] would uncover or learn of his involvement in these crimes,” the bail letter said.

Heuermann's attorney, Michael J. Brown, of Central Islip, said he first spoke with Heuermann about the new indictment Wednesday.

“He communicated that he is not guilty,” Brown told Mazzei.

Heuermann, dressed in a gray suit and navy blue tie, mostly looked down and in the direction of documents his attorney was holding, seeing the new details himself for the first time. He is scheduled to return to court July 30.

After the arraignment, Brown said his client was surprised he was being charged with more killings, an event the attorney said will significantly delay a possible trial.

“Rex is obviously horrified by the new charges,” Brown said. “New charges are always horrific and yeah, he's in a bad place due to the new charges.”

In a statement, attorney Robert Macedonio, of Islip Terrace, said Heuermann’s now former second wife, Asa Ellerup, “maintains the belief that her estranged husband is not capable of committing these heinous acts.”

“If Mr. Heuermann, committed these homicides, he was living a double life that Ms. Ellerup was unaware of,” Macedonio said.

Although Heuermann is not charged in the slaying of Valerie Mack, a sex worker who went missing in 2000 and is one of 10 apparent homicide victims tied to Gilgo Beach, the bail letter links him to her killing, noting that an analysis of Heuermann's electronic devices revealed a significant collection of violent bondage and torture pornography dating back to 1994.

The images showed various abuse and mutilation that prosecutors said “notably and largely coincide with how the remains of Sandra Costilla, Jessica Taylor, and Valerie Mack were discovered.”

The “manifesto” also referenced a dump site on Mill Road, the Manorville street where Mack’s remains were found around the time the document was created, Tierney said.

Ed Mack, the adoptive father of Valerie Mack, said he believes prosecutors will likely charge Heuermann in her death later this year. Tierney said Heuermann is a suspect.

Mack said he’s pleased to see how the investigation has progressed.

“It shows the police are looking at all the leads and data … it looks like they are really mining the evidence,” he said.

Heuermann, who was 30 years old when Costilla’s remains were found on Cove Road in North Sea in 1993, had previously not been charged in a killing committed earlier than 2007. He was arrested in July and charged in the deaths of three women — Megan Waterman, Melissa Barthelemy and Amber Lynn Costello — whose remains were found near Gilgo Beach in 2010. He was charged in the death of Maureen Brainard-Barnes in January.

Prosecutors believe Heuermann acted alone in the first four killings he was charged with and that the cause of each woman’s death was “homicidal violence.” Their bodies were found nude and bound, and they were contacted by burner phones consistent with Heuermann’s locations, prosecutors have said. Five hairs connected to Heuermann or a family member were recovered from three of the four sets of remains, according to prosecutors.

Heuermann was connected to the case primarily through cell site data, burner phone records and DNA evidence linking him to the women and the location where the bodies were found, prosecutors have said. A witness in Costello’s disappearance also provided a description of a truck linked to Heuermann, which helped establish him as a suspect and was later recovered from his brother’s property in South Carolina, prosecutors have said.

A cheek swab, obtained from Heuermann by court order since he’s been in custody, matched a mitochondrial DNA profile authorities who were surveilling Heuermann developed from a pizza crust and used napkin that allegedly were discarded in Manhattan, prosecutors have said.

The mitochondrial DNA profile developed from the pizza and napkin could not be excluded as a match to a hair found at the bottom of burlap used to “restrain and transport” the remains of Waterman, according to prosecutors.

Costilla, who also used the last name Cutello and was 28 when she was killed, had lived on Gates Avenue in Ridgewood, Queens, until around 1992, police said at the time. She also previously lived in an apartment in Flushing, Queens, property records show.

Costilla’s death had not been tied to the Gilgo Beach investigation until K-9 units spent five hours in April searching the wooded North Sea property where her remains had been found.

Instead, since as early as 1994, police had said Costilla’s death may have been linked to the killings of Colleen McNamee and Rita Tangredi, a narrative that continued through the 2014 arrest of John Bittrolff, who was eventually convicted in the other two murders.

Costilla was strangled and might have been raped, police said shortly after her remains were discovered. Similar to McNamee and Tangredi, her body was found nude, with her arms behind her back and wood chips present at the crime scene, the prosecutors who tried Bittrolff’s case said. But the DNA linking Bittrolff to the other two victims was not present at Costilla’s scene, former Assistant District Attorney Robert Biancavilla told reporters in 2014.

Detectives attempted to elicit a confession from Bittrolff in Costilla’s killing, according to court records, showing him her headshot and a photograph of her crime scene.

Ultimately, Bittrolff was never charged in Costilla’s death and Tierney said Thursday that DNA testing excludes him as a suspect. He is currently serving a 50-years-to-life sentence at Clinton Correctional Center in upstate Dannemora and appealing his conviction.

His attorneys with the Legal Aid Society of Suffolk County said in a statement to Newsday that Heuermann’s arrest in the killing of Costilla “calls into question” Bittrolff’s conviction on the other murders.

“Today, we know that Bittrolff was not the perpetrator of Sandra Costilla’s murder and we will be pursuing all legal avenues to challenge Mr. Bittrolff’s convictions,” reads the statement from attorneys Lisa Marcoccia and Felice Milani.

Prosecutors working on the Gilgo Beach killings said in court papers filed in March they had turned over 12 terabytes of data to Heuermann’s defense, including a transcript of the grand jury presentation, 85 grand jury exhibits, autopsy reports, photographs from the crime scene and the medical examiner’s office, search warrants and affidavits. Prosecutors said the defense also has been given paperwork from the Suffolk County Police Department and its crime lab, as well as outside laboratory documentation.

Tierney and Santomartino also said prosecutors also recently turned over nearly 400 complete leads, a total of more than 7,000 other persons of interest in the 13-year investigation.

With Anthony M. DeStefano, Akiya Dillon and Michael O'Keeffe