Criminologists at the Suffolk County Crime Lab are going through all items of evidence “inch by inch,” including a green Chevrolet Avalanche that belonged to the suspected Gilgo Beach killer.

The investigation into Rex Heuermann has stretched far beyond Long Island. Suffolk police confirm that investigators are looking into possible connections between Heuermann and unsolved cases around the nation. This includes Atlantic City, where four women were murdered in 2006.

MORE: Sources: Investigators believe at least 1 of Gilgo Beach murders took place at suspect's Massapequa Park home

Police have executed search warrants at Heuermann’s properties on Long Island and South Carolina. New York State Police recovered Heuermann’s vehicle from Chester County, South Carolina on Wednesday. The pickup truck is a key piece of evidence.

In 2010, a witness told police they saw that type of car parked in victim Amber Costello’s driveway shortly before her disappearance. The vehicle turned out to be a key piece of evidence that helped to lead investigators to Heuermann.

LIVE BLOG: Updates on the case as they happen 

“They were looking for that needle in the haystack,” said New York State Police Troop Commander Major Steve Udice. “It just shrunk that whole universe. They went from not knowing who it was that they were looking at to now having a direction.”

The match came six weeks after the formation of a new task force. As News 12 has reported, Suffolk police had already recovered years’ worth of cell tower data to build a “box” in the Massapequa Park area where they believed the victims had disappeared from.

A state police investigator assigned to the case started looking into that 2010 witness tip. She combed through databases, searching for any link to a Chevy Avalanche in the area. There could be hundreds of matches from the search results. Something about Heuermann’s vehicle stood out, though state police have not said what.

“I think what happens in investigations like these is that when you have different people, especially different people from different agencies looking at this, as you get a new set of eyes on these things, everybody looks at things differently,” Major Udice said.

MORE: ‘Inch-by-inch’ search for evidence in Gilgo Beach murder case continues as truck arrives at crime lab

Once the state police investigator narrowed down the vehicle search results, the task force looked at data alongside a two-mile radius of cell tower hits from burner phones used to contact some of the victims. There was a connection between these spots and the car’s locations.

“Once the car was identified, it was not very challenging to identify who the registered owner of the vehicle was,” said Major Udice.

As detectives began digging into Heuermann’s background, they say they learned his personal cellphone was often in the same areas, around the same time, as these burner phones. His cellphone location also matched up with some of the victims’ cellphone locations after their disappearance, according to court documents.

WATCH: DOCUMENTARY AND BACKGROUND INFORMATION - Gilgo Beach: Unsolved

The arrest has accelerated the investigation. Police are now able to conduct searches and interviews they could not do prior to the arrest, for fear of “tipping off” Heuermann. Prosecutors said Heuermann was keeping tabs on their investigation and searched more than 200 times for information on what they found.

Police are now interviewing people close to Heuermann, including his family.

The Suffolk County District Attorney’s Office is awaiting analysis of all the evidence and will have more information once that process is complete.