Last week, cops found another four bodies. Those bodies have not been identified, but Suffolk County Police said Tuesday that none of the remains belonged to Gilbert.
Cops obtained DNA samples of Gilbert's family last year and were able to quickly check the remains against those samples.
The police conclusion suggests that Gilbert is possibly a ninth victim of a serial killer.
Cops searched the brush along Gilgo Beach and neighboring Oak Beach last week, looking for the bodies of more women potentially killed and dumped in the thick vegetation, while other detectives worked to create a profile of the man who is stalking prostitutes online and killing them.
Suffolk County police have kept a tight lid on many of the investigation's details, commenting publicly only on the search efforts, including the canine units with cadaver sniffing dogs and a dozen police recruits from the academy brought in to help search for bodies.
In December, while searching for Gilbert, police stumbled on the killer's dumping ground, an area that has turned out to be a seven-mile stretch of beach as more bodies were discovered.
Zeins is confident that the killer will eventually slip up.
"The reason why we put erasers on pencils is because we all make mistakes. Whoever it is will make a mistake, and they'll get caught," he said.
Brad Garrett, an ABC News consultant and former FBI agent who has investigated dozens of high profile cases including the death of Washington intern Chandra Levy and the 2001 anthrax mailings, said he feels there is a distinct connection between the killer and the area.
"Given the volume of bodies in one location, it tells me the killer is very familiar with this stretch of road," Garrett said. "He grew up there, works there, lives there, or has a reason to frequent area. He feels comfortable stopping on that road at least eight times and dragging women to the sea grass line without worrying about being caught."
Though the profile of the Long Island killer is specific to the clues he has left behind, experts say there are typical traits many killers tend to have.
On average serial killers are white men between the ages of 20 and 40. They were often abused as children, but rarely have criminal records. They typically do not travel far to commit crimes, preferring instead areas they are familiar with and which they can move about without raising suspicion.
Serial killers are also often under-employed, Garret said, 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," Garrett said. "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."
Serial killers often target prostitutes, said Jack Levin, a criminology professor at Northeast University who studies serial killers.
"The most common victims are prostitutes," he said. "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."