Evidence technicians combed through Rex Heuermann’s Massapequa Park home for the eighth consecutive day on Friday. Investigators are searching for clues, such as DNA, that could lead back to some of the Gilgo Beach victims.

Dr. Lawrence Kobilinsky, forensic scientist and expert in DNA analysis, said analysts are likely focusing on recovering mitochondrial DNA. While most DNA degrades over time, mitochondrial DNA can survive the elements simply because there is so much of it.

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“The one chance you have to do a forensic DNA analysis is mitochondrial DNA, so they're looking for hair. Hair is ubiquitous at a crime scene,” explained Dr. Kobilinsky, professor at John Jay College of Criminal Justice. “They may find garments that they can't identify as his wife or his daughter, Heuermann’s. So what they would do is if they find hair on those items, they can do mitochondrial DNA and tell the origin to see if there's a match to one of the victims.”

Suffolk County District Attorney Ray Tierney said they are also looking for blood and trace evidence, in addition to DNA. The specificity and the sensitivity of next generation sequencing can give investigators significant information, even with small amounts of DNA that may be left after decomposition.

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However, collecting that evidence is a painstaking process, especially when there is so much to sift through. Police said Heuermann lived in his Massapequa Park home with his wife, two kids, and at least four pets.

“It’s probably the most difficult part of the whole process because if you don't collect properly, you're not going to be able to get any results, even after you analyze whatever you've got,” said Dr. Kobilinsky. “The other thing is you cannot overwhelm a laboratory with thousands and thousands of items.”

Investigators have entered Heuermann’s DNA into a statewide database to see if there are any connections between him and other unsolved cases. If there is a match, Dr. Kobilinsky said it is possible that police would know by now.

Police expect to continue searching Heuermann’s home through the weekend. They have also executed search warrants at his Amityville storage units and his property in South Carolina.

Detectives had been investigating Heuermann for more than a year prior to his arrest, but they said he was watching them too.

According to court documents, Heuermann searched more than 200 times over a 15-month span for details on the investigation into the murders of four Gilgo Beach victims. Prosecutors said he also repeatedly viewed hundreds of photos of the victims and their families.

Now that they have their suspect behind bars, police have a chance to ramp up their investigation and gather even more evidence.

“There were many things that could not be done because, had they been done, Rex Heuermann would have been tipped off,” said New York State Police Troop Commander Major Steve Udice. “Now that Rex Heuermann has been arrested, there's probably even more work to be done in the way of search warrants, that you're well aware of being executed, and interviews that are going to be conducted of different people, including family members.”

The investigation by the Gilgo Beach task force has focused on four victims, but police recovered seven other bodies in that area in 2010. Suffolk DA Tierney said they will continue to investigate those murders and look for potential connections to Heuermann.