Killings of 3 women in Long Island went unsolved for more than a decade. Here's how authorities tracked down the suspect

After the remains of four women were found near a beach in Long Island, New York, more than a decade ago, investigators say DNA evidence and cellphone data now point to a murder suspect - a local architect whose internet history showed him often searching the status of the case and details about the victims.

Rex Heuermann was arrested in New York City on Thursday, more than a year after a police task force explored his possible connection to the cold case known as the "Gilgo Four," named for the beach where the remains were found.

Heuermann, 59, was indicted on one count of first-degree murder and one count of second-degree murder in each of three of the killings - Melissa Barthelemy in 2009, and Megan Waterman and Amber Costello in 2010, according to the indictment. He pleaded not guilty Friday during his first court appearance on Long Island and was remanded without bail.

The defendant, who told his attorney he did not carry out the killings, is also the prime suspect in the 2007 disappearance and death of a fourth woman, Maureen Brainard-Barnes, according to a bail application from Suffolk County prosecutors. Heuermann has not been charged in the case, but the investigation "is expected to be resolved soon," the document states.

"Rex Heuermann is a demon that walks among us. A predator that ruined families. If not for the members of this task force, he would still be on the streets today," Suffolk County Police Commissioner Rodney Harrison said during a news conference Friday, and offered his condolences to the victims' families.

"To the family members of Amber Costello, Melissa Barthelemy and Megan Waterman. I can only imagine what you've had to endure over the last decade regarding knowing that your killer was still loose. God bless you," Harrison said before hugging a few people standing behind him.

Authorities had been left with little information after a search for a missing woman in 2010 led to the discovery of multiple sets of human remains at Gilgo Beach. By the time the remains of the missing woman, Shannan Gilbert, were found the following year, at least 10 sets of human remains had been recovered across two Long Island counties.