The devastated family of a murdered Long Island woman believes two mysterious calls from a Boston number -- one lasting 17 minutes -- to her cellphone around the time she disappeared may be the key to solving who killed her.
But Rebecca Koster's loved ones say Connecticut detectives have been unable to track down who called at about 4 a.m. on Dec. 4.
"We have no idea who this number belongs to," Koster's stepfather, Larry Ross, said yesterday. "This could be the key."
Ross, who said he'd been told the number was a prepaid AT&T cellphone, says his family has repeatedly dialed it.
The phone's voice mail feature had not been activated.
Connecticut State Police are investigating the murder of the 24-year-old home-health aide, whose stabbed and burned body was found dumped in a field in North Stonington. All they would say yesterday was, "We do not discuss details of an ongoing investigation."
Ross said cops were looking into the possibility that the killer may have used a ferry to cross Long Island Sound into Connecticut.
The Orient Point-to-New London ferry docks 13 miles from where the body was found just north of I-95, a main route to Boston. The Port Jefferson-to-Bridgeport ferry leaves a short distance from where Koster was last seen at the Butcher Boy Bar and Grill in Holbrook, LI.
Angela Smith, who tended bar that Friday night at Butcher Boy, said Koster came in with her boyfriend at 3 a.m. on Dec. 4 and left about 20 minutes later.
"She came in intoxicated. They're only here for a little bit, and then her boyfriend took her out," Smith told The Post. "She was annihilated. She couldn't talk. She came from another bar."
The boyfriend, Dan Mayor, 28, "came in the next night, and he said [that] she was missing but [that] he had dropped her off at her house and walked her to her door," Smith said.
The slain woman's mother, Barbara Ross, was sobbing yesterday at the family's Medford home while sending a message to the killer who had viciously hoaxed the family with text messages from Koster's missing phone.
"How would your mother feel to be tormented and tortured and made to believe there was hope when there was never any from the beginning?" she asked.
"I wanted to believe that so bad. Everyone wanted to believe it."
"And we can't even have an open casket because of the finalities of what you did," she said at another point. "Take a moment to think about that."
Anyone with information is asked to contact the Connecticut State Police at (860) 848-6500.