Rex Heuermann, the accused Gilgo Beach serial killer, has been charged with murder in the killing of Maureen Brainard-Barnes, who disappeared in 2007.

He was charged in July with the killings of Melissa Barthelemy, Megan Waterman and Amber Costello, whose bodies were found buried along a remote beach parkway.

Heuermann faces a second-degree murder charge in Brainard-Barnes' killing.

"This indictment marks a change in the investigation. The grand jury investigation into the so-called 'Gilgo Four' is over...and we will proceed with these cases in court," said Suffolk District Attorney Ray Tierney.

As for the other six sets of human remains discovered near Gilgo Beach, Tierney says the multiagency task force working the case is still investigating.

"We are going to let that investigation play out," he said.

According to court documents, the defendant’s family was out of state during Brainard-Barnes' murder. They were also out of state during the murder of the other Gilgo Four victims.

The family had checked into a hotel in Atlantic City on July 6, 2007 and remained there until approximately July 20.

Tierney says the murder took place around July 9, 2007 and that Heuermann joined his family in Atlantic City a short time after.

Tierney also said they recovered two burner phones from Heuermann at the time of his arrest, one of which was used to contact numerous sex workers.

It was also used to identify one of his aliases, Andrew Roberts, and a fraudulent email account, Sandbagger303@gmail.com. He says the Sandbagger account was used to search for torture porn and information about the Gilgo case.

Tierney says other devices, including laptops, phones and tablets, were also recovered. He says the defendant searched for information regarding "wiping" data from devices. He says those devices also linked Heuermann to the victims through Backpage ad searches and were used to contact Amber Costello hours before she was killed.

The DA also says nuclear DNA linked to Heuermann was found in hairs on a belt buckle that was used to secure Brainard-Barnes's lower body.

Heuermann is due back in court Feb. 6.