By Sabrina Souza, Jean Casarez and Lauren Mascarenhas, CNN

(CNN) — Rex Heuermann, the suspect in the Gilgo Beach killings, was charged with the murder of a seventh victim in a new superseding indictment released on Tuesday in Suffolk County court.

Heuermann was charged with second-degree murder in the killing of Valerie Mack, whose partial remains were found November 2000 on Long Island in New York.

“Your honor, I am not guilty of any of these charges,” Heuermann said in court Tuesday, shaking his head no.

Mack was a 24-year-old Philadelphia mother and worked as an escort at the time of her disappearance.

“The Mack family is emblematic of the other families in this case, who have steadfast stood by their loved ones and zealously guarded their memories,” Suffolk County District Attorney Raymond Tierney said in a news conference after the court appearance.

Attorney Gloria Allred, along with some family members of Heuermann’s alleged victims whom she represents, presented red roses to Mack’s parents on Tuesday. Many of them embraced the parents and shed tears during the emotional moment.

“We want the family to know they are not alone in their grief,” Allred said.

Heuermann’s attorney, Michael Brown, said Tuesday that his client is “adamant that he did not do these crimes.” Brown said Heuermann was surprised by the latest charge.

The judge scheduled the next hearing for January 15.

Parts of Mack’s remains were first found in a wooded area of Manorville by a group of hunters with a dog. The dog alerted the hunters to a plastic bag wrapped with duct tape and filled with additional bags that were holding human remains, which prompted the hunters to call 911, according to Tuesday’s bail application.

In May 2020, prosecutors used a DNA sample from Mack’s remains and worked with local law enforcement, a genetic genealogist from the FBI, and the Suffolk County crime laboratory to determine the remains belonged to Mack, according to the district attorney’s bail application.

Human hair found on Mack’s left wrist led prosecutors to the DNA profiles of Heuermann’s wife and daughter, Asa Ellerup and Victoria Heuermann.

Two forensic laboratories have now confirmed that hairs recovered on six of the seven alleged victims are “forensically tied” to Heuermann or members of his immediate family, or others he lived with, according to a legal filing.

During the initial investigation in Manorville in 2000, Mack’s head, hands, and right foot were not found at the scene and remained missing for approximately 11 more years.

In April 2011, Mack’s skull, hands, and right foot were discovered east of Gilgo Beach in Suffolk County, less than 1.5 miles east of where the remains of Jessica Taylor – who Heuermann is also accused of killing – were found, according to court documents.

There were similarities between the cutting instruments used to dismember Mack and Taylor, as well as the garbage bags containing their remains, the bail application says.

Investigators seized over 350 electronic devices from Heuermann’s residence after his arrest and found a “significant collection of violent, bondage, and torture pornography,” according to the document.

Investigators also found a Microsoft Word document they say Heuermann used to blueprint and plan out his kills, which was created in 2000, the same year Mack was murdered, the document notes.

In the months leading up to Mack’s murder, Heuermann accessed pornographic images featuring breast mutilation and bondage with rope, which coincide with Mack’s injuries and how she was found tied up, the document notes.

Tierney stressed Tuesday that the investigation is ongoing.

“We are here because the Gilgo task force has continued to work together to obtain not only evidence for the charged crimes, but has continued to work on other uncharged crimes as well,” he said.

Heuermann was initially arrested in July 2023 and charged with murder in the killings of four women whose bodies were discovered bound with belts or tape and wrapped in burlap along a stretch of off Ocean Parkway in Gilgo Beach in 2010.

Those victims – Melissa Barthelemy, Megan Waterman, Amber Costello and Maureen Brainard-Barnes – became known as the “Gilgo Four.” Heuermann pleaded not guilty to the charges related to all four.

Two additional second-degree murder charges were added in June 2024 for the deaths of Taylor and Sandra Costilla. Taylor was killed in 2003, and Costilla in 1993. Heuermann pleaded not guilty to those charges as well.

The women were among at least 11 sets of remains discovered near the waterfront in Long Island’s Suffolk County.

Correction: An earlier version of this story misspelled the last name of Valerie Mack.

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