James Yates pleaded guilty to second-degree murder after admitting he stabbed a prostitute at least twice and saw her bleeding to death, but did not call for help.
Now, nearly a decade after he was arrested in the killing, Yates's conviction has been overturned by the State Appeals Court.
Yates said that he stabbed Emily Hatch, 30, on April 12, 1995, after the two had sex and she told him that she had AIDS and tried to give it to him.
After his conviction, Yates asked a Superior Court judge to allow him to withdraw his guilty plea, saying his lawyer had never explained that a charge of second-degree murder could be reduced to manslaughter if he could show he was provoked.
The judge rejected his request, but yesterday, the Appeals Court overturned that ruling and ordered Yates to be allowed to withdraw his guilty plea.
The court found that the law on provocation should have been explained to Yates before he entered his plea. The law says that if a person kills another in the heat of passion after reasonable provocation, then the killing may be designated manslaughter and not murder because of the mitigating circumstances.
The Appeals Court said that because the law was not explained to Yates, his guilty plea was not made with all the facts before him.
David Procopio, a spokesman for Suffolk District Attorney Daniel Conley, said prosecutors will appeal the ruling to the state Supreme Judicial Court. Procopio declined to comment further.
Yates's appellate attorney, Richard Fallon, declined to comment on the ruling. Yates's original lawyer, John Conwell, could not be reached for comment yesterday.
Yates, then 24, initially told police he stabbed Hatch in self-defense after she and a man broke into his apartment in the city's Roxbury neighborhood.
Police found no evidence of a break-in.