Rex Heuermann has been charged with killing three women whose bodies were discovered along a stretch of Long Island's Gilgo Beach in 2010, bound with belts or tape and wrapped in burlap.
A married father accused by authorities of leading a double life, Heuermann faces three counts of first-degree murder for the killings of Melissa Barthelemy in 2009, and Megan Waterman and Amber Costello the following year, according to the Suffolk County District Attorney. He has pleaded not guilty and is being held without bail.
The 59-year-old New York architect is also the prime suspect in the disappearance and killing of a fourth woman, Maureen Brainard-Barnes, whose remains were found near the same spot. He has yet to be charged in that case.
Heuermann was first identified as a potential suspect in early 2022, shortly after a multi-agency task force was formed to examine cold cases involving nearly a dozen sets of human remains found along Long Island's South Shore between 2010 and 2011, including the Gilgo Four.
Here's what we know about the deaths of those four women:
Maureen Brainard-Barnes
Brainard-Barnes was 25 years old and believed to be a sex worker when she was last seen on July, 9, 2007. She had called a friend in Connecticut, where she lived, and said she had an "out call," according to Suffolk County police.
The young woman was reported missing by a friend to the Norwich Police Department in Connecticut on July 14. Her remains were found on December 13, 2010, on the north side of Ocean Parkway, near Gilgo Beach.
She is believed to be the first "Gilgo Four" victim.
Her sister, Melissa Cann, told CNN in 2011 that she desperately tried to solve the mystery of Brainard-Barnes's disappearance, scouring her emails and phone records, and staying in touch with families of the other victims.
Cann said her sister worked a seasonal telemarketing job and turned to escort services in desperation when left unemployed and facing eviction.
Melissa Barthelemy
Barthelemy was 24 years old when she was last seen on July 12, 2009, in the basement apartment where she lived in the Bronx, according to the Suffolk County police website on the Gilgo killings.
On the night she was last seen, Barthelemy, a sex worker, told a friend she was meeting a man and would be back in the morning, according to the police website.
Barthelemy's mother reported her missing on July 18. Records for her cellphone showed activity in Manhattan as well as Freeport, Massapequa and Lindenhurst on Long Island.
In July and August 2009, according to a bail application for Heuermann, Barthelemy's phone was used by a man to make taunting calls to the victim's family.
Steve Cohen, who was an attorney for Barthelemy's mother at the time, told CNN the caller said he killed her daughter.
"Do you think you'll ever see her again?" the unidentified male caller asked Barthelemy's sister on August 26, 2009, according to Cohen. "You won't. I killed her," he said and hung up.
In another phone call, just days after Barthelemy disappeared, Cohen said the unidentified male caller referred to the victim as a "whore" in a short conversation with her then-15-year-old sister.
In one call, the man described in graphic detail to the victim's sister what he had done sexually to Barthelemy, according to Cohen.
Barthelemy's remains were the first set of female remains found in bushes along an isolated strip of waterfront property. At the time, authorities were searching for another missing woman, Shannan Gilbert, a 23-year-old from Jersey City, New Jersey, who hadn't been seen since May 2010.
"I still don't sleep through the night thinking about all of it," Lynn Barthelemy, the victim's mother, told CNN in 2011.
She said she jotted down everything she learned about the case in a notebook and spoke regularly with families of other victims.
Investigators believe Barthelemy was the second of the women to be killed.
Megan Waterman
Waterman was 22 years old when she was last seen on June 6, 2010.
A resident of Maine, Waterman was last seen by her family boarding a Concord Trailways bus heading from Maine to New York, according to Suffolk County police.
She was a sex worker, police said. At 1:30 a.m. on June 6, she left the Holiday Inn Express on Long Island to meet a client, according to police.
Waterman was reported missing in Maine on June 8. Family members said it was unusual for her not to check on the daughter Waterman had left in their care.
Her body was found on December 13, 2010, near Gilgo Beach.
Waterman's family at one time used funding from a nonprofit human rights organization to hire a team of private investigators to help search for her.
Dottie Laster, a member of that team, told CNN in 2011 Waterman sounded starstruck when she called her mother to boast that her clients included doctors, lawyers and law enforcement officers.
Amber Lynn Costello
Costello was 27 years old and living on Long Island when she was last seen. She struggled with a heroin addiction and worked as an escort to help support her habit, according to Suffolk County police.
She was was last seen leaving her home on September 2, 2010, to meet a client. Her remains were found on December 13, 2010, near Gilgo Beach. She is believed to be the fourth victim.
Witnesses told investigators that the client she met the day she went missing had been at her home previously. They described the man as "a large, white male, approximately 6'4" to 6'6" in height" with "big oval style" glasses. A witness also said the man resembled an "ogre." Heuermann's bail application noted the description from these witnesses in 2010 matched Heuermann.
Costello's sister, Kim Overstreet, told CNN in 2011 that she took out an ad hoping to catch the killer. The ad implored other women who work as escorts to call Overstreet. She wanted them to tell her if they ever encountered a client who was threatening or just didn't feel right.
"What happened to Amber eats at me every day," Overstreet said at the time. "Finding out who did this consumes me. I stay up all night doing research and trying to re-trace her last steps."
Witnesses also said the man drove a first-generation Chevrolet Avalanche -- a key clue that prosecutors said helped lead them to Heuermann.