Accused Gilgo Beach serial killer Rex Heuermann to be charged in murder of Valerie Mack — his 7th

Accused Gilgo Beach serial killer Rex Heuermann will be charged with a seventh murder — the November 2000 death of Valerie Mack, police sources told The Post Tuesday.

The parents of Mack, whose remains were found in Gilgo Beach and Manorville, are expected in court Tuesday morning when Heuermann is arraigned on the new charge.

Prosecutors named Heuermann, 60, as a suspect in Mack’s death in June based on evidence, including detailed notes about serial killings that were seized from his Massapequa Park home.

Heuermann has already pleaded not guilty to charges stemming from the murders of six women whose remains were discovered near Gilgo Beach and other parts of eastern Long Island.