Rex Heuermann, the man dubbed the ‘serial killer’ of Gilgo Beach, has been accused of killing his seventh victim

Suspected Gilgo Beach serial killer Rex Heuermann has been charged with murdering a seventh victim.

Heuermann was indicted for the 2000 killing of Valerie Mack at a Long Island courthouse Tuesday morning.

Mack was a 24 year-old Philadelphia woman who vanished 24 years ago. Partial remains were found in Manorville, Long Island, in November that year.

Heuermann has been charged with Mack’s murder after her body was reexamined using the latest DNA analysis. 

He was named as a suspect back in June after detailed notes about serial killings were discovered at his Massapequa home.

Heuerman, 61, was arrested in 2023 and charged with the murder of six women – at least four of whom were sex workers before their deaths.

He had previously stated that he was not guilty of the murders of six women: Sandra Costilla, Jessica Taylor, Melissa Barthelemy, Amber Lynn Costello, Megan Waterman, and Maureen Brainard-Barnes.

But prosecutors say they have tied him to the killings using cellphone site data and DNA.

Rex Heuermann, pictured in court in July, has now been charged with murdering a seventh victim, Valerie Mack 

Valerie Mack disappeared in 2000 and parts of her body were discovered in Long Island that November 

They also say that an alleged manifesto detailing how he carried out the slayings was discovered on a hard drive in his basement.

According to the document, Heuermann supposedly wrote down a list of tasks to be done before, during, and after the killings. These tasks included checking the weather, setting up a location for the crime, and jotting down notes for improvements for the “next time.”

Within one segment titled ‘BODY PREP,’ there were instructions to remove the victims’ heads, hands, tattoos, and any evidence of torture. It is also claimed that Heuermann made a note to thoroughly wash the bodies, including all body cavities, after the crimes.

Another section, ‘THINGS TO REMEMBER,’ appears to highlight lessons from previous killings that should be heeded, according to prosecutors.

The entries describe the importance of sleeping properly ‘BEFORE HUNT,’ using thick rope, and limiting noise to increase ‘PLAY TIME.’

In a section titled ‘POST EVENT,’ there were reminders such as ‘change tires,’ ‘burn gloves,’ ‘dispose of pics,’ and ‘have story set.’

In addition to the hard drive, prosecutors say they found a book in Heuermann’s possession by the retired FBI agent John Douglas, The Cases That Haunt Us. 

They say the planning document also referenced specific pages in another work by Douglas, Mind Hunter, that allude to the personality types of serial killers and personality profiles of those who use mutilation and sexual violence.

The first victim, 24-year-old Melissa Barthelemy, was discovered by Suffolk County Police on December 11, 2010. The body of Megan Waterman, 22, from Maine, was found two days later

Heuermann is also charged with killing Amber Costello (left) and  Maureen Brainard-Barnes (right) 

Investigators in April spent days searching a property in the eastern Long Island hamlet of North Sea, where Sandra Costilla’s body was discovered in 1993

Jessica Taylor vanished in 2003 while working as an escort in New York City. Some of her remains were discovered in Manorville that year

 Jessica Taylor vanished in 2003 while working as an escort in New York City. Some of her remains were discovered in Manorville that year. 

Other remains were found in a 2011 search of the beach scrub by the side of Ocean Parkway, the road where the other Gilgo Beach victims were found.

She had been decapitated and both of her arms were severed. Moreover, a tattoo on her torso had been ‘severely obliterated by a sharp object,’ per officials.

Prosecutors said one entry in the planning documents suggested he was involved in the death of Mack, who was found dismembered in the same vicinity as Taylor.

Since late 2010, police have been investigating the deaths of at least 10 people — mostly female sex workers — whose remains were discovered along an isolated highway not far from Gilgo Beach on Long Island’s south shore.

The victims had disappeared over a span of at least 14 years. Vexed police officers made only halting progress in identifying possible suspects.

Investigators long said it was likely that not all of the deaths were the work of the same killer.

Developing story, check back for updates…