Originally Published: 14 JUL 23 08:55 ET

Updated: 14 JUL 23 12:23 ET

By Kristina Sgueglia, Brynn Gingras, John Miller and Ray Sanchez, CNN

(CNN) — A New York architect is in custody for the Gilgo Beach murders, an unsolved case tied to at least 10 sets of human remains discovered since 2010 in suburban Long Island, according to two law enforcement sources.

This is the first arrest in the long-dormant case, which sparked conflicting theories about whether a serial killer was responsible.

The man in custody was identified as Rex Heuermann, multiple sources told CNN Friday. How many murders he has been connected with is unclear.

Authorities were executing a search warrant at an address registered to him in Massapequa, the sources said. A court appearance is scheduled later Friday morning, according to the Suffolk County DA’s office.

Heuermann is a registered architect who has owned the New York City-based architecture and consulting firm, RH Consultants & Associates, since 1994, according to his company’s website.

“Throughout the years, Rex Heuermann has provided services to other city agencies, not for profit agencies, builders, developers and individual owners of buildings,” the company website said.

In 2022, Heuermann was interviewed for the YouTube channel “Bonjour Realty.” He spoke about his career in architecture, and said he was born and raised in Long Island. He began working in Manhattan in 1987.

CNN has reached out to Heuermann’s company for comment.

The killings have baffled authorities since the discovery of the first set of female remains among the bushes along an isolated strip of waterfront property on Gilgo Beach.

Suffolk County officials, including investigators and prosecutors, and the FBI are set to announce a “a significant development in the investigation by the Gilgo Beach Homicide Investigation Task Force,” at 4 p.m. ET Friday, according to a joint news release.

At an impromptu news conference earlier Friday, county officials said an indictment will be made available.

County Executive Steve Bellone said the arrest is “a major, major step forward … to bring closure to these families and to bring justice to the victims in this case.”

The murder mystery has confounded county officials for years. In 2020, they found a belt with initials that may have been handled by the suspect and launched a website to collect new tips in the investigation.

Police said some victims identified had advertised prostitution services on websites such as Craigslist.

The mystery began in 2010 when police discovered the first set of female remains among the bushes along an isolated strip of waterfront property on Gilgo Beach while searching for Shannan Gilbert, a missing 23-year-old woman from Jersey City, New Jersey.

By the time Gilbert’s body was found one year later on neighboring Oak Beach, investigators had unearthed 10 sets of human remains strewn across two Long Island counties.

The grim discoveries generated widespread attention in the region and sent waves of fear across some communities on Long Island’s South Shore.

Authorities later said they believe Gilbert’s death may have been accidental and not related to the Gilgo Beach slayings.

Still, Gilbert’s disappearance led to the discovery of the bodies of four women who were found in bushes along a quarter-mile stretch of Ocean Parkway in Oak Beach.

Additional remains were uncovered in neighboring Gilgo Beach and in Nassau County, about 40 miles east of New York City. They included a female toddler, an Asian male and a woman initially referred to as “Jane Doe #6,” investigators said.

In 2020, police identified “Jane Doe #6” was as Valerie Mack, a 24-year-old Philadelphia mother who went missing two decades earlier.

Mack’s partial remains were first discovered near Gilgo Beach in 2000, with additional dismembered remains found in 2011, according to the Suffolk County police.

Last year, Suffolk County police formed a task force that included the FBI, state police, and the offices of the county district attorney and sheriff to strengthen what police called “one of the most consequential homicide investigations in the history of Long Island.”