Gilgo Beach suspect Rex Heuremann is charged with two additional murders of Jessica Taylor and Sandra Costillo

Gilgo Beach serial killer suspect Rex Heuermann has been charged with two additional murders.

Heuermann, of Long Island, was indicted by a grand jury on Thursday for the murders of 20-year-old Jessica Taylor in 2003 and 28-year-old Sandra Costilla in 1993. 

Charging documents say the alleged serial killer was linked to the new victims through DNA, thanks to male hair found on both of their remains.

Unlike Heuermann's other alleged victims, Costilla was not believed to be a sex worker. And her remains were found in a wooded area of Southampton, Long Island. 

The Gilgo Beach killer got his nickname because of the coastal spot where he chose to dump his other victims, but Costilla does not fit that pattern.

Heuermann, who has pleaded not guilty in the deaths of four women , appeared Thursday in state court in Riverhead

Heuermann, 60, is now accused of killing six women in total over a span of 30 years.

He made an appearance at a Long Island court Thursday morning as the new charges can be put to him. Dressed in a dark suit and light blue shirt, his head was lowered as he stood by his attorney Michael Brown. 

His wife Asa and their children were not present and were in Florida for a pre-planned vacation.

Heuermann has pleaded not guilty to the murders of four other women, who were sex workers. 

An earlier report, citing law enforcement officials, wrongly claimed Heuermann was to be charged with the murder of Valerie Mack who vanished in Atlantic City in 2000. 

The new charges come just weeks after police searched Heuermann's dilapidated home in Massapequa Park, Long Island, focusing on the basement.

Prosecutors say they found 'planning documents' that Heuermann allegedly used to map out his killings in a hard drive found during the search.

The headless and handless body of Taylor, 20, was discovered in the woods of Manorville, New York, in 2003. The rest of her remains were discovered in 2011 over 40 miles away near Gilgo Beach on Long Island.

The headless and handless body of Jessica Taylor, 20, was discovered in the woods of Manorville, New York, in 2003

Sandra Costilla, 28, was tied to the Gilgo Beach investigation after an April search the property were her remains were found. Unlike the other victims in the case, Costilla has never been described as a sex worker by law enforcement

Costilla, who lived in Queens but was from from Trinidad and Tobago, was tied to the Gilgo Beach investigation after an April search the property were her remains were found. 

She was strangled and was possibly raped, police said after her remains were found in Southampton Town. Her body was found naked with her hands tied behind her back. 

Unlike the other victims in the case, Costilla has never been described as a sex worker by law enforcement. 

Search teams with K9s were seen sweeping the wooded area in Manorville over three days.

Heuermann was arrested in July and initially charged with killing Melissa Barthelemy, 24, Megan Waterman, 22, and Amber Lynn Costello 27.

Multiple agencies searching Manorville location in connection with Gilgo Beach investigation

The Heuermann family home in Massapequa Park was torn apart by authorities as they combed the property for evidence

Search crews removing items from the basement of Rex Heuermann's home 

In February, he was also charged with the murder of Maureen Brainard-Barnes, 25.

The women were found wrapped in burlap and buried along the remote stretch of Ocean Parkway on Long Island's South Shore over a decade ago.

Heuermann, an architect, has pleaded not guilty to all counts and currently remains in jail awaiting trial. A date for trial has not yet been set.

The Gilgo women's remains were discovered during the search for 23-year-old Shannan Gilbert, an escort from New Jersey who had vanished in May 2010 after making a frantic 911 call.

Her remains were found along the same stretch of coast in December 2011 - and it was her body that led police to the discovery of the 'Gilgo Four'.

No one has ever been charged in Gilbert's death and police said it may have been accidental - but her family believe she was murdered.

The women were among 11 found on the desolate stretch of coastline close to Heuermann's Long Island Home between 2010 and 2011.

The first victim, 24-year-old Melissa Barthelemy, was discovered by Suffolk County Police on December 11, 2010. The body of Megan Waterman, 22, from Maine, was found two days later

Heuermann is also charged with killing Amber Costello (left) and  Maureen Brainard-Barnes (right) 

The women known as the 'Gilgo Four' were discovered close to Heuermann's Long Island home. However, other bodies - including those of sex workers - have been found in the area

All of the victims worked as escorts who advertised themselves on Craigslist.

Heuermann was linked to the killings by DNA on the burlap used to transport the bodied which was compared to samples taken from a pizza crust and napkin that were discarded outside his Manhattan architectural firm, police said.

The samples boasted a 99.96 percent match, according to law enforcement officials.

Cops said they were alerted to Heuermann as a potential suspect after a witness linked Heuermann's Chevrolet Avalanche to Costello's murder.

The car was then tied to Heuermann's cellphone records, which allegedly linked him to locations related to the murders.

Surrounded by law enforcement, victims' families, attorneys and others, Suffolk County District Attorney Ray Tierney, center, speaks to reporters on Thursday

Elizabeth Bacziel, Jessica Taylor's mom, was seen at the press conference on Thursday

The indictment stated that Heuermann had used different burner phones to contact each of his victims.

Cops also accused Heuermann of using Barthelemy's phone to make taunting phone calls to her family from the comfort of his office.

Her sister Melissa told how she was bombarded with threatening phone calls from the killer who boasted of the killing and was keeping tabs on her movements.

Vess Mitev, a lawyer for Heuermann's two adult children, said the family was closely monitoring the developments.

'The hearing is yet another mile marker in this macabre saga, where they continue to be unfortunate bystanders,' he said.