Gilgo Beach serial killer Rex Heuermann defiantly delivers a killer stare in a new mug shot released Tuesday — one day before he’s set to get shipped off to prison for life.

Heuermann, 62, admitted in court in April that he strangled eight sex workers to death and dumped their bodies in desolate stretches of Long Island between 1993 and 2010.

The plea deal came with a guaranteed sentence of three life terms, which is expected to be handed down in a Riverhead courthouse Wednesday.

The new mug shows the hulking architect with a chilling, defiant stare — a sharp contrast to the sinister smirk he flashed in court when he pleaded guilty.

The Gilgo Beach killings loomed over Long Island for more than 30 years before finally finding closure with Heuermann’s arrest in 2023 and eventual guilty plea.