The New York architect facing murder charges in a string of deaths known as the Gilgo Beach killings was charged on Tuesday in the death of a seventh woman.

Rex Heuermann pleaded not guilty to killing Valerie Mack, whose remains were first found on Long Island in 2000. Mack, 24, had been working as an escort in Philadelphia and was last seen by her family that year in New Jersey.

Some of Mack’s skeletal remains were initially discovered in Manorville, New York; authorities found more of her remains about 50 miles (80 kilometers) west, in Gilgo Beach, more than 10 years later. They were unidentified until genetic testing revealed her identity in 2020.

Human hair found with Mack’s remains was sent for testing earlier this year and found to be a likely match with the genetic profile of Heuermann’s daughter, prosecutors said in court papers. His daughter is not accused of any wrongdoing and would have been 3 or 4 years old when Mack died.

Heuermann, 61, is charged with killing six other women whose remains were found on Long Island. He has pleaded not guilty to all the charges.

“The lives of these women matter,” Suffolk County District Attorney Ray Tierney said at a news conference with Mack's parents and other victims' relatives. “No one understands that more than the families.”

Mack's parents didn't speak. Four other victims' relatives gave the Macks roses and hugs and, through an attorney, expressed their sadness and solidarity.

“They were, and they are, loved. And they are missed every day by those who knew them and who had a strong bond with them,” said Gloria Allred, who represents the families of Melissa Barthelemy, Maureen Brainard-Barnes, Jessica Taylor and Megan Waterman.

Outside of court, Heuermann’s lawyer Michael Brown disputed evidence presented in Mack’s death, saying the DNA technology used to connect her and other victims to Heuermann has never been deemed reliable in a New York case.

He also argued that Tierney’s office has yet to produce proof any victims’ DNA was found in Heuermann’s home, including the many weapons and tools seized during recent searches of the property.

“There’s something a little weird about these allegations,” Brown said. “Something that doesn’t sit right.”

The investigation into the Gilgo Beach killings dates back to 2010, when police searching for a missing woman found 10 sets of human remains in the scrub along a barrier island parkway, prompting fears of a serial killer.

Over the years, investigators used DNA analysis and other clues to identify the victims, many of whom were sex workers. Police also began reexamining other unsolved killings of women on Long Island.

The case has dragged on through five police commissioners, more than 1,000 tips, and doubts about whether there was a serial killer at all.

Heuermann, who lived with his wife and two children in Massapequa Park on Long Island and commuted to a Manhattan architecture office, was arrested on July 13, 2023. At that point, he was charged with murdering Barthelemy, Waterman and Amber Lynn Costello.

Earlier this year, he was charged in the deaths of three other women — Brainard-Barnes, Taylor and Sandra Costilla.

In a June court filing, prosecutors said they had recovered a file on a hard drive in Heuermann’s basement that he used to “methodically blueprint” his killings — including checklists with tasks for before, during and after, as well as lessons for “next time.”

In court papers on Tuesday, prosecutors said the document, which was created the same year as Mack’s murder, includes details that align with her case.

For example, it names “Mill Road” — a road near where Mack’s first remains were found — under the heading “DS,” which investigators believe stands for “dump site.”

The document also lists “foam drain cleaner” under “Supplies.” Prosecutors say that on Oct. 3, 2000, Heuermann’s phone records appear to show him making two calls to a Long Island plumbing company, and he paid another company the following month to check his mainline drain.

In recent searches of Heuermann’s home and office, authorities say they found old magazines and newspapers with articles about the Gilgo Beach killings and investigation that prosecutors believe he kept as “souvenirs” or “mementos.” Among them was a July 29, 2003, copy of the New York Post that included an article about the investigation into Mack and Taylor’s remains.

Tierney said Tuesday that evidence points to Heuermann’s home as the scene of the killings — in most cases, when his family was out of town.

Heuermann’s estranged wife, Asa Ellerup, said in a statement that she still does not believe her husband was capable of committing the crimes he’s accused of.

The couple’s now grown children said in a separate statement they remain “steadfast in observing the legal process play itself out, no matter how long it takes or how difficult it is.”

Authorities have still not charged anyone in the deaths of some other people whose remains were found on Long Island.

Among them is an unidentified male victim who died in 2006 and likely presented outwardly as a female, and Karen Vergata, whose remains were discovered in 1996 but only identified through new DNA analysis in 2022.