Read more :Irish-born cop heads serial killer investigation

Read more: Three other victims of Long Island’s Craigslist Killer revealed

Police in Nassau County, where eight bodies have been found, have widened their search as they believe the 'Craigslist Killer's' killing spree could have been spread over four years.

The four bodies recovered most recently appear to be older. It is believed that the first murder could have taken place in 2007. The police are now looking at old missing person reports in an attempt to identify the bodies and determine how long this killer has been on a rampage.

The police have been trawling over the area of Gilgo and Oak beaches, an area of seven and a half miles onLong Island's coast, New York. Their search will continue into next week.

The search began back in December 2101 when they police started searching for Shannan Gilbert. Although they have discovered eight other bodies none of them appear to be Gilbert.

Gilbert and the first four victims of the 'Craigslist Killer' were all prostitutes who advertised their services on the classifieds website

Suffolk Chief of Detective Dominick Varrone said that the first four bodies found in December were buried in a quarter mile area, just 50 feet from the side of the Ocean Parkway and 500 feet apart. The latest four bodies were buried some distance away, much deeper and in thorny bushes.

It is believed that the first of the victims went missing in July 2007 while the latest was September 2010.

The first four women, found in December, were all Craigslist escorts in their 20s. Each body was wrapped in burlap (a type of sack cloth). The professions and the manner in which they were buried prompted Irish-born Police Commissioner Richard Dormer to begin a hunt for a serial killer back in December.

The first victim was Maureen Brainard-Barnes, 25, who was last seen in Manhattan on July 9, 2007. Melissa Barthelemy was 24 when she vanished two years later almost to the day. She was followed by Amber Lynn Costello, who was 27 when last seen in early September last year. The last to be identified was Megan Waterman, a 22-year-old who disappeared last June. All four were wrapped in hessian.

The other four bodies are yet to be identified.

Last week the discovery of the four other bodies prompted the police to resume a widespread search of a seven-mile stretch of beach. This led to the discovery of three additional victims yesterday, but tests have not yet revealed who they are.

Sherre Gilbert, Shannan's sister, told the New York Post how shocked he was that none of the eight bodies were her sister. Her sister had a metal implant in her upper body which makes her easily identifiable.

She said " My heart sank when I got the call from the detective…We have to find my sister, she’s out there somewhere.

"Out of all the bodies we all thought one had to be her. He was shocked as well.

"Now I’m left with more questions that are unanswered."

It is believed that the police are now looking at possible links between this killer and the remains of four women found on a beach near Atlantic City in 2006.

The Craigslist Killer is fast becoming the most prolific killer in New York State in recent years.

Read more :Irish-born cop heads serial killer investigation

Read more: Three other victims of Long Island’s Craigslist Killer revealed