Suffolk County District Attorney Ray Tierney will make a rare move and prosecute accused Gilgo Beach serial killer Rex Heuermann himself, his office said Wednesday.

“Tierney will be the lead prosecutor in the case against Rex Heuermann. He intends to prosecute this case fully and bring justice to the victims of this alleged serial killer,” spokeswoman Tania Lopez said in a statement.

It’s the first time Tierney has prosecuted a crime since he took office last January — and he has already taken an unusually hands-on role in the high-profile case.

The county’s top prosecutor presented evidence to a grand jury that led to the indictment of the hulking 59-year-old architect, then took a lead role at the the accused killer’s arraignment on July 14.

Heuermann was charged on July 13 in the slayings of Amber Lynn Costello, 27, Melissa Barthelemy, 24, and Megan Waterman, 22 — three of the “Gilgo Four” whose remains were found on Gilgo Beach in 2010.

He is is also considered a “prime suspect” in the killing of Maureen Brainard-Barnes, whose body was found near the three women, prosecutors have said.

Earlier this week, investigators seized dozens of guns and other items from Heuermann’s Massapequa Park home and are analyzing them as evidence potentially linking him to other victims.

“The DA’s office will continue to work with our [Gilgo Beach] Task Force partners to develop new evidence and prepare the case for trial,” Lopez said.