Police believe they have the Long Island serial killer in custody more than a decade after remains belonging to at least 10 people were discovered near Gilgo Beach, N.Y.

Rex Heuermann, a 59-year-old man from Massapequa Park, was arrested on July 13 in connection to the murders of three women, according to officials. He was charged with three counts of first-degree murder and three counts of second-degree murder, pleading not guilty to all at an arraignment on the following day, according to his defense attorney Michael J. Brown.

"There is nothing about Mr. Heuermann that would suggest that he is involved in these incidents," Brown said in a statement to E! News. "And while the government has decided to focus on him despite more significant and stronger leads, we are looking forward to defending him in a court of law before a fair and impartial jury of his peers."

In a press conference on July 14, Suffolk County Police Commissioner Rodney Harrison called Heuermann "a demon that walks amongst us, a predator that ruined families." 

"However, even with this arrest, we're not done," Harrison continued. "There's more work to do in the investigation in regards to the other victims of the Gilgo Beach bodies that were discovered."

Heuermann's arrest comes 13 years after the disappearance of Shannan Gilbert, a 24-year-old sex worker from New Jersey who vanished in May 2010 after leaving a residence in Oak Beach. 

In the police's search for Gilbert, investigators uncovered other human remains along a remote highway adjacent to Gilgo Beach, including those belonging to Melissa Barthelemy, 24, Megan Waterman, 22, Amber Lynn Costello, 27, and Maureen Brainard-Barnes, 25. 

Gilbert's remains were found in 2011, the same year police unearthed remains from four other people, including Jessica Taylor, 20, and Valerie Mack, 24. Investigators believe the murders occurred over a period of nearly 26 years.

Read on for more details about the case, including its suspect.

Who is Rex Heuermann, the Long Island murders suspect?

Heuermann has been identified by authorities as the prime suspect in the long-unsolved Gilgo Beach murders. The 59-year-old lives in Massapequa Park, a town north of South Oyster Bay and Gilgo Beach, where remains belonging to at least 10 people were discovered alongside an adjacent highway.

According to Billy Baldwin, Heuermann was his high school classmate. "Berner High School. Massapequa, New York. Class of 1981," tweeted the actor, who—along with his brothers Alec Baldwin, Stephen Baldwin and Daniel Baldwin—grew up on the south shore of Long Island. "Mind-boggling… Massapequa is in shock."

What is Rex Heuermann's job?

In a 2022 interview with Bonjour Realty, Heuermann identified himself as an architect and an architectural consultant. "Born and raised on Long Island," he said at the time. "Working in Manhattan since 1987."

Who is Rex Heuermann accused of murdering?

Heurmann has been charged with three counts of first-degree murder and three counts of second-degree murder for the killings of Melissa Barthelemy, 24, Megan Waterman, 22, and Amber Lynn Costello, 27. Remains belonging to the three women were found near Gilgo Beach in 2010, when police were investigating the disappearance of 24-year-old Shannan Gilbert. (Gilbert's remains were found in 2011.)

How did police find Rex Heuermann?

In 2022, authorities performed a comprehensive review of the Gilgo Beach case and learned that Heuermann was the registered owner of a first-generation Chevrolet Avalanche—the same make in vehicle mentioned in a past tip about the disappearance of Costello, according to court documents obtained by NBC News.

Further investigation into Heuermann found that his cellphone billing records allegedly corresponded to cell site locations for burner phones used to arrange meetings with the three victims, police said in the docs. Furthermore, police said his billing records also corresponded to a phone used to make "taunting calls" to Barthelemy's sister.

"A review of these records, as well as Heuermann's American Express records, showed numerous instances where Heuermann was located in the same general locations as the burner cellphones used to contact victims Barthelemy, Waterman, and Costello," the documents read. "Significantly, investigators could find no instance where Heuermann was in a separate location from these other cellphones when such a communication event occurred."

How did police allegedly connect Rex Heuermann to the Long Island murders?

In addition to the cellphone billing records, a DNA sample taken from hair found on the burlap used to wrap Waterman's remains shares the same profile to a DNA sample taken from a pizza box that Heuermann threw out, according to authorities. As investigators noted in a bail application, "It is significant that Defendant Heuermann cannot be excluded from the male hair recovered near the 'bottom of the burlap' utilized to restrain and transport Megan Waterman's naked and deceased body."

Investigators also found found female hair not belonging to the victims in their remains. A DNA sample taken from the unknown hairs matched DNA believed to belong to Heuermann's wife, authorities said.

A police investigation determined Heuermann's wife was out of town during the killings, and that "it is likely that the burlap, tape, vehicle(s) or other instrumentalities utilized in furtherance of these murders came from Defendant Heuermann's residence, where his wife also resides, or was transferred from his clothing," court documents read.

How did Rex Heuermann plea to the murder charges?

During an arraignment on July 14, Heuermann pleaded not guilty to three counts of first-degree murder and three counts of second-degree murder, per NBC News. According to the outlet, a judge remanded him without bail.

(E! and NBC News are both part of the NBCUniversal family.)