Gilgo Beach killings: Suspect charged in death of Philly woman Valerie Mack

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 Amber Lynn Costello, Megan Waterman and Melissa Barthelemy.

Earlier this year, he was charged in the deaths of three other women — Maureen Brainard-Barnes, Sandra Costilla and Jessica Taylor. He has pleaded not guilty to all charges.

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 to tick off before, during and afterwards, 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 disappearance and deaths of Mack and Taylor.

Prosecutors are also looking into the death of Karen Vergata, whose remains were first discovered in 1996 and finally identified in 2022 after a new DNA analysis.

In September, authorities released new renderings of an unidentified victim who was found in 2011. Officials said the victim, whom for years they had identified as male, may have presented outwardly as female and died in 2006.