A sadistic killer stabbed a 24-year-old woman to death

A sadistic killer stabbed a 24-year-old woman to death, hid her mutilated body and then used the victim's cell phone to taunt her family by sending text messages that made them think she was alive, say police.

After a night of partying, Rebecca Koster was dropped off at her home by her boyfriend and two friends. She was home alone when 30-year-old Evan Ganthier reportedly slipped in and plunged a knife into her chest four times.

Then Ganthier, of Central Islip, reportedly wrapped the body in a blanket, dumped in in the trunk of his car and drove it to a remote spot in Connecticut. The remains were discovered the next day. But it took forensic experts five days to ID Koster because Ganthier reportedly skinned a tattoo off her back, hacked off her head, fingers and toes, and set the remains on fire.

During those five days, Ganthier reportedly sent her family the twisted text messages as a sick prank. Three months later, cops cuffed Ganthier, and he reportedly confessed to the heinous homicide. But in court, he recently pleaded not guilty to second-degree murder. He is being held without bail.

Meanwhile, the tragedy still mystifies Koster's family.

"I don't know who he is," says Koster's stepfather, Larry Ross of Medford.

"No one in the family, nor her friends, know who he is. It's like he dropped out of the sky to kill my daughter.

"We're glad they arrested somebody. It's been horrific, endless sleepless nights. And the worst part is it won't bring Rebecca back.

"But we still want to know why. No one deserves this. He sent messages to my wife."