Authorities Claim Rex Heuermann Kept 'Souvenirs' and 'Mementos' While Charging Him with 7th Murder

Heuermann pleaded not guilty on Tuesday to Mack's murder in Suffolk County court.

The charge comes after Heuermann was initially arrested in 2023 and charged with the murders of Amber Lynn Costello, Melissa Barthelemy, and Megan Waterman. Earlier this year, he was also charged with the murders of Maureen Brainard-Barnes, Jessica Taylor and Sandra Costilla.

He was linked to Mack's murder via forensic evidence -- including a hair near her body allegedly matching the DNA of his wife and daughter. Per prosecutors, the manner of Mack's death and dismemberment also matched a "planning document" found on Heuermann's devices.

A superseding indictment released Tuesday gives more insight into the ongoing investigation and its findings -- including the discovery of what prosecutors call "mementos" and "souvenirs" at Heuermann's home and office following a search.

Inside a cardboard box in his Manhattan office, Gilgo Homicide Task Force agents found a PEOPLE magazine from November 7, 2016 with the headline "‘BODIES ON THE BEACH: HUNT FOR THE LONG ISLAND SERIAL KILLER: Who is the cold-blooded murderer killing women and dumping their bodies on a New York Beach?” on the cover.

In his home, they also discovered a New York magazine from 2011 with a "Serial Killer on Long Island" cover story.

While those two clippings were both found in 2023, a May 2024 search of his home turned up newspapers inside his primary bedroom -- including a New York Post with an article entitled, "Serial Killer Eyed in L.I. Slay." The article, per prosecutors, included details on both Mack and Taylor's disappearances.

Papers in the basement, meanwhile, included a 1993 article entitled "Body Discovered in Woods," which referenced Costilla's homicide investigation. All the papers were believed to have been store-bought and not subscriptions.

"Based on the totality of the investigation, the Task Force believes Rex A. Heuermann sought, purchased, and kept these publications as, inter alia, 'souvenirs' or 'mementos' of his crimes, serving as a reminder of the events that occurred throughout the murders of each victim," noted prosecutors in the docs.

Remains were first discovered in November 2000, when hunters came across a plastic bag wrapped with duct tape. Inside the bag, police discovered a torso, legs and arms; the victim's head and hands had been severed from her body, while her right leg had also been cut off mid-calf.

She became known as Jane Doe #6; her head, hands and right foot weren't found for 11 years. In 2020, using DNA samples from her remains, she was identified as Mack, who authorities believe was a sex worker in both Philadelphia, Pennsylvania and Atlantic City, New Jersey.

Per the docs, she was also "known to 'street walk,' i.e., wander the streets looking for sex work."

The Suffolk County Medical Examiner’s Office later determined she was killed between September 1, 2000 and November 19, 2000. The Medical Examiner's Office also discovered injuries to the victim's breast, which the docs note were "likely the result of post-mortem mutilation of the victim’s breast with a sharp object."

During the examination, a human hair was also discovered by the victims left wrist, inside the sealed garbage bags.

The hair allegedly came up as a match for both Asa Ellerup and Victoria Heuermann, Heuermann's wife and daughter. Additional forensic testing also allegedly showed the hair "is substantially more likely to have derived from a person genetically identical to Victoria Heuermann's DNA profile, thereby linking evidence from yet another crime scene to the Defendant through his immediate family."

Victoria would have been between 3 and 4-years-old at the time.

In the docs, prosecutors reiterated some of the findings after executing search warrants on Heuermann's electronic devices -- this time linking them to Mack's murder as well.

"As previously detailed, an analysis of these devices has revealed Heuermann’s significant collection of violent, bondage, and torture pornography, currently dating back to 1994," they wrote. "Moreover, in the months leading up to Ms. Mack's disappearance and murder, the Task Force uncovered pornographic images accessed by Heuermann which include, breast mutilation, and the tying up of women with rope, which largely coincide with a.) the injuries inflicted on Ms. Mack's breast and b.) how the rope ligatures were utilized on Valerie Mack."

They also noted that during the month of September 2000, "investigators observed a large uptick in downloads of pornographic images depicting Bondage, Discipline, Sadism, and Masochism."

See how his lawyer previously defended Heuermann's internet activity here.

Prosecutors later pointed out increased internet uses of GilgoNews.com, which followed the murder investigation, in the days leading up to Mack's identity being revealed in 2020.

The docs also resurfaced details from a Word Document investigators believe "to be a 'planning document' utilized by Heuermann to methodically blueprint and 'plan out' his "kills." Prosecutors pointed out that the original document "appears to have been created in the year 2000, which notably coincides with the year Valerie Mack was murdered."

Investigators believe the "planning" document "substantively relates to the Mack investigation in other respects," pointing out how they believe it advises for "small" victims and the use of dump sites, "ROPE/CORD," "BAGS/TAPE" and "SAW/CUTTING TOOLS." The doc also suggests to "REMOVE HEAD AND HANDS" AND "REMOVE ID MARKS [TATTOOS..."

Mack, according to the Gilgo Homicide Task Force's investigation, allegedly had a tattoo of her son's name on her foot/ankle.

"The examination of the victim's body in 2000 revealed no tattoos on the victim's left foot/ankle," they wrote. "Based on the foregoing, the Gilgo Homicide Task Force members believe the Defendant amputated Ms. Mack's lower right leg at the mid-calf to inhibit and/or delay the identification of Ms. Mack's tattoo and therefore, Ms. Mack."

Summing up the case, prosecutors wrote:

Based on the foregoing, Rex A. Heuermann is now charged with the murders of seven victims. Of note, two independent laboratories have forensically linked evidence from six of seven crime scenes to Defendant Heuermann and/or members of his immediate family, or individuals with whom Heuermann resided.

Second, the HK Planning Document's creation in 2000, the same year Valerie Mack was murdered, as well as its description of DS-1, or the first "dump site" as Mill Road, which is where the remains of Ms. Mack were discovered, further emphasizes the document's relevance to the Valerie Mack homicide investigation.

Furthermore, the dismemberment of Ms. Mack's right leg, where she had a tattoo of her son's name, was clearly intended to inhibit the identification of Ms. Mack, which is corroborated by the HK Planning Document, its presence on Heuermann's laptop computer, and the mutilation of Jessica Taylor's tattoo in a similar fashion.

Finally, the Gilgo Homicide Task Force members believe that Rex A. Heuermann's possession of numerous publications relating to not only the "Gilgo Four," but also Sandra Costilla, Valerie Mack, and Jessica Taylor, indicates the Defendant’' attempts to remind himself of the events that occurred throughout the murders of each victim, revealing Rex A. Heuermann's utter lack of disregard or remorse for his actions, or the victims.