Philadelphia (CNN) -- Philadelphia Judge M. Teresa Sarmina ruled Friday to stay the execution of Terrance Williams and grant a new penalty phase in the case, after finding that authorities had suppressed evidence of alleged sexual abuse.
Williams, 46, had been scheduled to be executed on October 3 for a 1984 slaying in which he beat Amos Norwood to death with a tire iron.
Sarmina found "reasonable probability" that the verdict might have been different had allegations of abuse surfaced during the initial case, noting that the relationship between the two men had been established but not disclosed.
Williams attorney Shawn Nolan said the defense team is "very gratified" by the decision, having maintained that information about the alleged abuse was withheld from the trial and that Williams' life should instead be spent in a cell.
The sexual abuse began when Williams was 6 years old, his attorneys have said. They argued that the jurors who convicted Williams more than 25 years ago were told that it was a robbery-homicide case and never learned of the abuse allegations.
Philadelphia District Attorney Seth Williams said Friday that he would appeal the decision. He has said the abuse allegations are hearsay and "a last-ditch effort to escape punishment."
"In the 28 years since the murder of Amos Norwood, these new allegations only came to light just a few months ago, and (Williams) is not the one making the allegations."
Announcing the scheduled execution, Pennsylvania Gov. Tom Corbett's office described the brutal Philadelphia killing.
Williams and accomplice Marc Draper led Norwood, 56, to an area near a cemetery, forced him to lie on the ground, tied him up, gagged him and stole his valuables, the governor's office said in a statement.
"Williams and Draper repeatedly beat the man with a tire iron and a socket wrench and then drove away in the victim's car. Williams later returned and burned Norwood's body," the statement said. Draper is serving a life sentence.
On September 17, the state's Board of Pardons failed to reach the unanimous agreement required to recommend clemency. Three members of the five-person panel voted in favor of asking Corbett to consider granting clemency. But the two other board members voted against the petition.
Since the execution date was set, a number of high-profile supporters have called for clemency in the case, including Pennsylvania Attorney General Linda Kelly. More than 360,000 people have signed an online petition asking authorities to spare Williams' life. Norwood's widow has also asked for the execution to be called off.
But Norwood's daughter wants the execution to go forward, the Philadelphia district attorney's office said.
She said Friday that accusations of sexual abuse were false and asked the court to uphold the death penalty.