Heuermann was arraigned on murder charges in Suffolk County Court this past July for the killings of Melissa Barthelemy, Megan Waterman, and Amber Lynn Costello. He's also the prime suspect in the disappearance and murder of Maureen Brainard-Barnes.
Prosecutors are expected to announce a new grand jury indictment charging Heurmann with a fourth murder when he returns to court in Riverhead on Tuesday, Jan. 16, according to ABC News, which cited sources.
It's unclear if that new charge is connected to the Brainard-Barnes case.
The 59-year-old Heurmann wan architect who worked on Fifth Avenue in Manhattan and resided in Nassau County in the village of Massapequa Park just miles north of the site where their bodies were found -- in a grassy area of Gilgo Beach, a barrier island off Long Island's south shore in the Suffolk County town of Babylon.
Investigators have found 11 bodies on Gilgo Beach and identified five of them.
The time frame for the murders is from April 20, 1996 to Dec. 13, 2011.
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