Gilgo Beach murders: What questions remain following Rex Heuermann's arrest?

The shocking revelation that New York City architect Rex Heuermann had been charged with three murders in connection to women found dead along Long Island's Gilgo Beach provided some answers about the decade-old case. But it also generated just as many new questions.

Heuermann has been charged with the murders of Melissa Barthelemy, Megan Waterman and Amber Costello, and has been called the "prime suspect" in the death of a fourth woman, Maureen Brainard-Barnes. All four women were found in the same area of the beach, bound in the same fashion and with three covered in burlap.

However, six other bodies were found in the same area in late 2010 and early 2011, and police investigators said the investigation into Heuermann is far from over.

Here are some of the biggest questions that remain even after Heuermann's arrest.

What about the other 6 bodies found on Gilgo Beach? Who were the victims?

Heuermann has only been tied to four murders, known colloquially as the Gilgo Four because they were the first four women discovered in December 2010. The four remains were found along the beach about 500 feet from each other, according to police.

In the ensuing months, police found four more sets of remains along the same stretch of beach and two other sets of remains on nearby beaches.

On March 29, 2011, police found the remains of Jessica Taylor, a 20-year-old sex worker who had gone missing in 2003. Other parts of Taylor’s body had been found nearly eight years before in Manorville, New York, in eastern Long Island.

A week later, on April 4, 2011, police found the remains of an unidentified woman and a toddler about a mile and a half east of Taylor's remains and a little over 2 miles east of the Gilgo Four. The woman would later be identified as Valerie Mack, whose partial remains had been discovered in Manorville in 2000. Police have suggested there may be a connection to Taylor's remains, some of which were also found in Manorville.

The baby's remains were later discovered through DNA evidence to be the child of a woman whose remains were found on April 11, 2011, in Nassau County, Long Island. Other parts of her remains were found in 1997.

On the same day the woman and young child were discovered, an unidentified Asian male was discovered closer to the remains of the Gilgo Four. The person has never been identified. Authorities said the person was about 17 to 23 years old and had died five to 10 years before being discovered.

The final set of remains often tied to the case were those of an unidentified woman found near Tobay Beach in Nassau County on April 11, 2010. She has also never been identified, and, like the mother of the infant, was not found on Gilgo Beach like the other eight victims.

Is Heuermann tied to any other murders?

While police aren't naming any other victims in connection with Heuermann, they are leaving the door open to the possibility that he was involved in more killings. Investigators spent all weekend going through Heuermann's home in Massapequa Park looking for evidence.

"There's more work to do in this investigation regarding the other victims of the Gilgo Beach bodies," Suffolk County Police Commissioner Rodney Harrison said Friday.

Heuermann's DNA has been entered into a statewide database, and detectives are now checking to see if his DNA or behavior fit unsolved murders and missing persons cases in New York City, an NYPD official told ABC News.

"We're coming to the end of our initial investigation of the so-called Gilgo Four," Suffolk County District Attorney Ray Tierney told ABC News Monday. "We'll prosecute those cases, and while we're doing that, we're going to continue to investigate those other ones. And just like with the initial parts of our investigation, we'll allow the evidence to dictate what we do and will allow the evidence to speak for us. We're not going to engage in conjecture."

Investigators have long believed it was possible there was more than one killer because of the different conditions of the victims. Additionally, the wooded stretches along Ocean Parkway were long known as dumping grounds for bodies.

Why were police searching for the bodies and how is Shannan Gilbert connected?

Police discovered the first four women while searching for Shannan Gilbert, a missing sex worker who had called police after fleeing from a home in the area, saying, "They are trying to kill me," according to the family's lawyer, John Ray. Gilbert had gone missing in May 2010, but authorities were unable to locate her or her remains throughout the summer despite several searches.

It wasn't until December that Suffolk County police came across the remains of the Gilgo Four, and then the subsequent other bodies.

Gilbert's remains were finally found in December 2011 in nearby Oak Beach.

In January 2020, then-Suffolk County Police Commissioner Geraldine Hart said Gilbert's death "doesn't match the pattern of the Gilgo Beach homicides." The medical examiner has officially ruled her death as an accidental drowning. Gilbert's family, however, has been steadfast in saying that they believe she was murdered.

Why did it take so long to arrest Rex Heuermann?

Authorities first discovered the bodies of the Gilgo Four in December 2010, but Heuermann wasn't arrested until almost 13 years later.

When announcing the arrest of Heuermann on Friday, Tierney credited the formation of a task force dedicated to solving the Gilgo Beach murders in January 2022 as a turning point in cracking the case.

On March 14, 2022, previous evidence led to Heuermann being identified as a suspect to investigators for the first time, according to court records. Shortly before Costello's disappearance, a man matching the description of Heuermann had shown up to her home as a client for her services, only for Costello to pull a ruse that ended up with her taking his money and a man chasing Heuermann from the home. The suspect was driving a Chevy Avalanche truck, as described by a witness interviewed after Costello's disappearance.

When investigators began searching for a man who owned a Chevy Avalanche in the area of Gilgo Beach, they came across Heuermann's name.

Another hindrance to investigators at the time of the discovery of the four bodies were strands of hair that could not be tested by available DNA methods at the time.

A female hair was discovered on a belt used to tie Brainard-Barnes' legs together, while two female hairs were discovered on Waterman -- one on the tape used to bind her body -- and one female hair was found on a piece of tape used to bind Costello's body. By using mitochondrial DNA testing not available in 2010, all of the hairs were determined to be from the same woman -- with more than a 99% match for Heuermann's wife, according to court documents. Police don't believe she was involved, as she was out of the country when the killings occurred, according to cellphone records noted in the court records, but that Heuermann had the hairs on his body.

Mitochondrial DNA testing was also done on a single male hair found on the burlap used to wrap Waterman's body, which was a 99.96% match for Heuermann himself.

What was the motive for the killings?

The biggest remaining question may be why, if the allegations are true, did Heuermann allegedly commit the murders?

The extensive bail application form that outlines how and why Heuermann was arrested makes only hints as to the motive. The court record outlines that Heuermann was regularly searching for "sadistic, torture-related pornography" and showed an interest in searching for other known serial killers, but it doesn't specifically provide a motive.

Harrison provided a simple explanation during Friday's press conference: "Rex Heuermann is a demon that walks among us."

ABC News' Aaron Katersky, Ella Torres and Emily Shapiro contributed to this report.