He could go free as early as Saturday because of a legal technicality.
The family of Jeffrey Walter, who at 23 was stomped to death nearly a decade ago, is angry and heartbroken.
His mother, Gail Diguglielmo, spent the last ten years putting the pieces of her life back together.
"I just told him that he murdered my son and he's getting away with murder a second time," she said.
Now Mark Petronio, the man who brutally murdered her son in a drug deal gone bad, is about to be released from jail
"I'm ripped apart that I could sit and look at a man that killed my son knowing that he is now free 15 years earlier. He's free. It's heartbreaking," she said.
Back in 2000, Petronio murdered Walker after the two men fought over a drug deal. He sprayed mace on Walker's face and stomped on his neck, and then buried the body in a backyard in Patchogue.
He was later convicted of 2nd degree murder with depraved indifference. Them the New York Court of Appeals changed the law interpreting the definition of the charge.
"The federal court vacated the conviction correctly finding that the defendant was factually innocent of depraved indifference murder," defense attorney Kevin Keating said.
Petronio agreed to plead to the lesser charge of manslaughter, which means the convicted killer will likely serve 10 of the 25 years he was originally sentenced to serve.