Serial killers are also often underemployed, said Garret, and clues at the beach may help investigators determine his job, an important step in narrowing the circle of suspects.
"Some of the women were wrapped in burlap bags," said Garrett. "It's possible that that those bags came from some aspect of his life. Did they have fertilizer in them? Did they have coffee? What might that mean about his job?"
Garrett, however, said that does not mean investigators should immediately assume the killer is a "blue collar transient type."
Instead it's feasible that the killer "leads a normal life," he said. He "could be married and functions well in society. But he has this other dark side to his personality."
Gilbert, like the other identified women, was a prostitute. She disappeared on May 1, 2010 after arraigning to meet a client through Craigslist. An oak Beach, N.Y., resident told authorities that a woman he believes was Gilbert came to his home at 4:45 a.m. that morning. She fled when he tried to call police.
Serial killers often target prostitutes, said Jack Levin, a criminology professor at Northeast University who studies serial killers.
"The most common victims are prostitutes. They're easy prey. They get right in the car with a killer. Families are slow to file missing person reports and there is little pressure on police to solve the case because it's a criminal killing a criminal," he said.
Police would not confirm the genders, ages or identities of the newly discovered bodies. They would not comment on the level of decomposition or whether these bodies, like the others, were wrapped in burlap.