Investigators are looking for any potential "trophies" in serial killer suspect Rex Heuermann's Chevy Avalanche seized from his brother's Chester, South Carolina, property earlier this week, according to a search warrant.

Heuermann, a 59-year-old Manhattan architect and father of two, is charged with three counts of first-degree murder and three counts of second-degree murder in connection with the mysterious slayings of Melissa Barthelemy, Megan Waterman and Amber Lynn Costello, whose remains were discovered on Long Island, New York, in 2010. Heuermann is also a prime suspect in the murder of Maureen Brainard-Barnes, who was also found dead near Gilgo Beach more than a decade ago.

The New York State Police, in collaboration with the Chester County Sheriff's Office and the FBI, seized two Chevy Avalanches — a black Avalanche in New York and a green Avalanche in South Carolina — tied to Heuermann's alleged crimes.

Police are now searching for "trophies," such as personal items belonging to victims, including but not limited to their "telephones, articles of clothing, jewelry, identification, notebooks, ledgers, Bibles, personal effects and/or photographs or recordings depicting the victims," inside the green Avalanche, the July 14 search warrant for the vehicle states.

GILGO BEACH MURDERS; NEW YORK STATE POLICE, FBI IMPOUND EVIDENCE FROM SOUTH CAROLINA

New York State Police tow Chevy Avalanche from South Carolina in Gilgo Beach murder investigation

New York State Police tow a Chevy Avalanche from South Carolina in the Gilgo Beach murder investigation. (Audrey Conklin/Fox News Digital)

Investigators are also looking for any forensic evidence — such as DNA from fingerprints, hair, nails, or other human fibers inside the vehicle — and any other materials from the vehicle that may assist with their investigation into the Gilgo Beach murders.

READ THE SOUTH CAROLINA SEARCH WARRANT:

Police listed black leather belts, devices used to "stamp" leather products, camouflage burlap fabric, duct tape and other signature items Heuermann allegedly used to restrain and kill his victims, according to New York court documents.

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Gilgo Beach murders suspect Rex Heuermann mugshot

Rex Heuermann, who owns a Las Vegas timeshare, was charged with murder in New York. Las Vegas police are looking to see if he is involved in any of their unsolved cases. (Suffolk County Sheriff’s Office via AP)

"[E]ach of the four victims were found similarly positioned, bound in a similar fashion by either belts or tape, with three of the victims found wrapped in a burlap-type material," a bail application in Heuermann's case reads.

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The green Chevy Avalanche was registered in Heuermann's brother's name at the time police seized it from his property. 

Heurmann belt

An evidence photo of a leather belt with embossed initials which was found at a Gilgo Beach crime scene during the initial investigation. (Suffolk County Police Department)

Craig Heuermann lives on a rural street in Chester. His house is barely visible from the road, and his driveway is blocked off by a gate with two no-trespassing signs, one of which says, "No warrant/No entry."

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Rex Heuermann also owns several plots of undeveloped land near his brother's house in Chester. A neighbor told Fox News Digital earlier this week that Craig told him Rex planned to retire in Chester and buy out the neighborhood.

Craig Heuermann's front gate with two 'no trespassing' signs

Rex Heuermann and his brother, Craig Heuermann, own secluded plots of land in Chester, South Carolina. (Fox News Digital)

Rex Heuermann was living in a Massapequa Park home on Long Island with his family at the time of his arrest. Police took the 59-year-old suspect into custody outside his Manhattan office on July 13 due to concerns about his weapons arsenal at his Long Island residence.

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New York State Police have searched Rex Heuermann's Messapequa Park home and his storage unit for evidence related to the case.

Authorities carry items out of Rex Heuermann's home in Massapequa Park

Authorities execute a search warrant of Rex Heuermann’s home in Massapequa Park, New York, on Tuesday. (Mega for Fox News Digital)

It is unclear if police will search his land in South Carolina.

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Suffolk County District Attorney Raymond Tierney said last week that more charges could be filed against Heuermann as investigators determine the suspect's connections to the first "Gilgo Four" victim, Brainard-Barnes, who was 25 when she disappeared in 2007.

The search for missing escort Shannan Gilbert, 24, led police to the discovery of seven additional victims in a wooded area up and down the coast of Gilgo Beach. All the victims were sex workers, aside from a toddler, according to authorities.

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Heuermann was tied to the crimes through DNA evidence and cellphone data. The suspect allegedly called at least one victim's family after her death and taunted them, according to court documents.

The murders have remained unsolved for more than a decade and have been the source of documentaries like "The Killing Season," which debuted in 2017; a Netflix show in 2020; and a book.

Fox News' Chris Eberhart and Michael Ruiz contributed to this report.