Rex Heuermann, the suspected Long Island serial killer, , prosecutors in New York announced on Thursday. In total, New York authorities have now charged Heuermann in the killings of six women that occurred over the course of three decades.

The new charges come after police investigators conducted searches of Heuermann’s Long Island home and a wooded area tied to the Gilgo Beach serial killings.

“The investigation continues, and that investigation has been expanded both to the bodies that have been found on Gilgo [Beach] and beyond,” Suffolk County District Attorney Ray Tierney told reporters Thursday. “This case continues.”

The latest charges against the suspected serial killer

Heuermann, a 60-year-old married father and former architect, was charged Thursday with second-degree murder in the 2003 death of Jessica Taylor, 20, and the 1993 death of Sandra Costilla, 28, according to prosecutors.

In July 2003, some of Taylor’s bodily remains were discovered in Manorville, N.Y., her skull, hands and forearms were found along a highway near Gilgo Beach.

According to investigators, phone records showed that Heuermann’s wife and children were out of town at the time Taylor was killed.

“[This] would have allowed Defendant Heuermann unfettered time to execute his plans for Ms. Taylor, which included the decapitation, dismemberment, and transportation of her remains, without any fear that his family would uncover or learn of his involvement in these crimes,” .

The killing of Costilla was long thought to have been by another person. Costilla’s remains were found in Southampton, N.Y., in 1993.

Hair remains found on Taylor and Castillo’s bodies were linked to Heuermann through DNA testing, forensic experts said.

As a result of investigators searching Heuermann’s home, they seized hundreds of electronic devices. They discovered a “planning document” on a hard drive found in his basement used to “methodically blueprint” his killings, .

Investigators also discovered the electronic devices contained a large amount of violent bondage and torture pornography. “That material was very similar to the condition that the two latest victims were left in,” .

The so-called ‘Gilgo Four’

Heuermann was first and charged with first-degree murder for the deaths of Melissa Barthelemy in 2009, Megan Waterman in 2010 and Amber Costello in 2010, all of whom were sex workers in their 20s.

Then in January of this year, in connection with the death of Maureen Brainard-Barnes, a 25-year-old sex escort who disappeared in 2007.

All of the remains of these victims were found over a decade ago, bound in a deserted spot on the north side of Long Island’s Ocean Parkway, near Gilgo Beach.

What’s next

Heuermann on Thursday pleaded not guilty to the two new murder charges. He previously pleaded not guilty to the other four murder charges. The judge ordered that he remain in jail without bail.

His next court date is scheduled for July 30. A trial date has not been set.