Accused Gilgo Beach serial killer Rex Heuermann has been charged with a seventh murder: the death of Valerie Mack, whose remains were first found 24 years ago, according to a superseding indictment unsealed Tuesday.

A hunter’s dog discovered Mack’s decapitated body in a wooded area of Manorville on Long Island on Nov. 19, 2000. Her remains were bound with rope inside a black plastic bag which was wrapped with duct tape, according to a bail application that accompanied the new indictment.

Both of her hands had been severed from her body and one of her legs was cut off, the document said.

The rest of Mack’s remains were found more than a decade later, in April 2011, along Ocean Parkway near Gilgo Beach, authorities said.

Prosecutors said they linked Heuermann to Mack’s death in part through a mitochondrial DNA analysis of a female hair found on Mack’s body. It matched the profiles of Heuermann’s wife and daughter, the bail application said. At the time of Mack’s murder, Heuermann’s daughter would have been between 3 and 4 years old.

Prosecutors said they also linked Heuermann to Mack’s death through evidence recovered on some of the 350 electronic devices they seized from him that include his “significant collection of violent, bondage and torture pornography” dating back to at least 1994. This online collection included images of mutilation and tying up women with ropes, two things prosecutors said are consistent with injuries inflicted on Mack and how she was bound, officials said.

Investigators said they found one document that they believe Heuermann used to “plan out” his kills. The document was created in 2000, the year Mack was killed. Under a section named “supplies,” Heuermann allegedly listed “rope/cord,” “saw/cutting tools,” and “foam drain cleaner.” Under a section labeled “DS,” believed to stand for “dump site,” Heuermann allegedly listed one of the locations where Mack’s remains were found, officials said.

The document also included a “body prep” section with a note to “remove head and hands,” according to the bail application.

Heuermann, 61, is charged with one count of second degree murder in connection with Mack’s death.

The New York architect was initially arrested in July 2023.

Heuermann has pleaded not guilty in the murders of six women: Melissa Barthelemy, Megan Waterman, Maureen Brainard-Barnes, Amber Costello, Jessica Taylor and Sandra Costilla. The first victim was found in 1993 and the last victims were found in 2010.