Rex Heuermann, an architect from Long Island who works at a firm in New York City, was taken into custody Friday in connection with some of the killings from over a decade ago ... according to multiple reports.

You may recall, the Gilgo Beach murders case started capturing national attention way back in 2010 ... when police discovered four bodies wrapped in burlap during a search for Shannan Gilbert, a sex worker who vanished on Long Island.

The bodies, known as the "Gilgo Four," were ultimately identified as Amber Lynn Costello, Maureen Brainard-Barnes, Megan Waterman and Melissa Barthelemy. The woman were all reportedly sex workers in their 20s.

Police have long believed a serial killer was responsible for the women's deaths ... but the investigation never really turned up much over the years, until Friday's arrest.

In total, 11 sets of human remains have been found on Gilgo Beach ... including Gilbert's and those of Valerie Mack, a sex worker who had been missing for over 2 decades ... plus a man and a toddler.

Heuermann was arrested after being matched with DNA, according to the New York Post, and he's expected to be arraigned later today.

Police have cordoned off Heuermann's home in Massapequa ... and the place is crawling with law enforcement.

The district attorney is set to address the arrest around 4 PM ET Friday during a news conference.