"We need to go to forensic ... dentistry ... and the last stop is to do the DNA analysis," Suffolk County Medical Examiner Yvonne Milewski said.
Forensic psychiatrist Michael Welner said that the high level of decomposition will make identifying the cause of death difficult.
"Many investigators of serial killers focus on signatures and approaches that a serial killer may have taken ... a calling card. A calling card is a lot harder to identify with decomposition so advanced," Welner said.
Police also told ABC News that they are looking at a possible connection to the 2006 unsolved murders of four prostitutes 160 miles away in the boardwalk area of Atlantic City in 2006. They were found lying in a drainage ditch.
"We have been in contact with authorities in Suffolk County. ... It would not be fair for us to comment on their investigation," Atlantic County Prosecutor Ted Housel said in a statement to ABC News on Wednesday.
If it does prove to be the work of a serial killer, it wouldn't be Long Island's first.
In 1993, Joel Rifkin was convicted for murdering 17 women. In 1987, Richard Angelo, nicknamed the "angel of death," murdered 25 patients.