Did Long Island serial killer taunt sister of victim?

(CBS/WCBS) - A report has been published saying that that the possible Long Island serial killer may have taunted the teenage sister of victim Melissa Barthelemy, a prostitute whose body was among four found by police last December.

Pictures: Long Island serial killer's victims?

According to The New York Times, officials say Barthelemy's sister received a series of phone calls from Barthelemy's phone that terrorized the family.

Barthelemy's mother, Lynn, told the paper that the calls all lasted less than 3 minutes, and that the man kept the family "hopeful" until the last call.

"In the final call, he said he had killed her," Lynn Barthelemy told the Times. The paper reports that when Barthelemy's sister told the caller she wanted to see her sister again, he said he'd killed her after having sex with her, then hung up and didn't call back.

Crews have uncovered at least 10 sets of human remains along the coastline in both Nassau and Suffolk Counties, including a skull, the bones of a toddler and the remains of four missing prostitutes.

Law enforcement sources told CBS News there may be two patterns and two killers, perhaps separating the first four remains, who have all been identified as prostitutes who advertised on Craigslist, and the six sets of remains that were more recently found.

Those six sets of remains are being DNA tested in an attempt to identify them. If and when they are identified, investigators will try to locate family members for more information about the victims' backgrounds with the hope that it will lead them to the victims' killer.

Complete Coverage of the possible Long Island serial killer on Crimesider