Williams was 17 when he fatally stabbed a 50-year-old high school sports booster during a sex-linked argument at the man's apartment. He had turned 18 when he and a friend fatally beat a 56-year-old church deacon, Amos Norwood, in a cemetery five months later.
Williams, a gifted quarterback who led his high school to a city title, was having sex with men throughout his teens in exchange for money, gifts and clothes. He says Norwood had been sexually abusing him since he was 13. The jury heard only that Norwood was killed in a robbery. Sarmina relied on original police files she unearthed in ruling Friday that prosecutors had "sanitized" the real story, perhaps affecting the jury's decision to sentence Williams to death.
The Supreme Court will now ask for briefs as prosecutors appeal her finding.
Only three people have been executed in Pennsylvania since the U.S. Supreme Court restored the death penalty in 1976.
Gary Heidnik was executed in 1999 for the murders of two women he had imprisoned in his Philadelphia home. The others were executed in 1995: Leon Moser for the 1985 murders of his wife and two daughters in suburban Philadelphia; and Keith Zettlemoyer for the 1980 slaying of a friend who planned to testify against him in a robbery trial.
Associated Press writer Peter Jackson contributed to this report from Harrisburg, Pa.