NEW YORK ( CNN ) -- After a nearly year-long investigation , police say they now believe 10 sets of human remains uncovered along a desolate stretch of Long Island , New York , beach are linked to a single killer . `` The theory is now that we 're dealing with one serial killer , '' Suffolk County Police Commissioner Richard Dormer told CNN affiliate WABC on Tuesday . He noted the killer did not `` necessarily do the same thing all the time . '' `` What 's common here is the dumping ground , '' he added . Dormer previously said that only the bodies of four females uncovered in December were thought to be the work of a serial killer or killers . It is not clear what prompted the change . Authorities have sifted through more than 1,000 tips related to the case . But it 's unclear whether they have shed any light on an investigation that has drawn state and federal agents and garnered national attention . In June , police upped the ante in their search for a culprit . The reward for information leading to an arrest -- once topping out at $ 5,000 -- was raised five-fold , making it the largest offered in Suffolk County history . It was an apparent bid to fill out a case that some fear has gone cold . `` We 're hoping the increased reward money will encourage somebody to come forward by calling the police in respect to the families and to ( the ) victims , '' Lt. Robert Donohue said at the time . At least 10 sets of human remains have been found in Nassau and Suffolk counties since December . But the woman whose disappearance triggered the searches , 23-year-old Shannan Gilbert , remains missing . The New Jersey woman was last seen in May 2010 at a private party at a home in Long Island 's Oak Beach community . The first four bodies have since been identified . They , like Gilbert , had advertised for prostitution services on websites such as Craigslist . Their remains were found among bushes along a quarter-mile strip of beachfront property , according to police . More human remains were found on March 29 and April 4 . Suffolk County District Attorney Thomas Spota said in May that the newly found remains were not believed to be connected to the first four victims . In September , authorities released composite sketches of what two unidentified victims might have looked like . Authorities at the time said the evidence suggested two other killers dumped bodies along Ocean Parkway in Gilgo Beach , about 40 miles east of New York City . `` This investigation is not an episode of 'CSI ' or 'Criminal Minds ' that is going to be solved in a one-hour period , '' Spota said of the serial killer probe . `` Most likely , it ... is going to take a very long period of time to complete . '' Spota was not immediately available for comment Wednesday regarding police statements that the killings are now thought to be the work of a single killer .
Police say they think a single serial killer is responsible for bodies found in Long Beach . Police previously said only the first set of murders could be the work of a killer or gang . The body of the woman who triggered it is still missing . The women who were killed advertised prostitution searches on websites .