Williams' only legal hope is an emergency petition asking a Philadelphia judge to stay execution based on newly discovered evidence that Williams had been sexually molested throughout his life - including for five years by the man he murdered.
Williams' lawyer, Shawn Nolan, assistant chief of the death-penalty unit at the Federal Defender's Office in Philadelphia, said the victim, Amos Norwood, 56, had a sexual relationship with Williams that began when Williams was 13.
And in January, Nolan said, Williams' admitted accomplice recanted his original testimony that Norwood was killed in a robbery.
In a Jan. 9 sworn statement, Marc Draper said Williams killed Norwood because of the abusive nature of their sexual relationship. Police coerced him into saying robbery was the motive, he said.
None of that information - including background on Williams' physical abuse by his mother and stepfather, and childhood sexual abuse by a neighbor and a teacher - was presented to the Common Pleas Court jury that condemned Williams to death in February 1986.
"The jury didn't know about any of these things," Nolan said. "And it's important. A number of jurors have told us that if they had known about it, they wouldn't have sentenced him to death."
According to interviews excerpted in court documents filed by Nolan last month, all five jurors the lawyers located also said they voted for death because they were under the mistaken impression that a life sentence would have allowed Williams to be released on parole.
Pennsylvania does not permit parole for people sentenced to life for first- or second-degree murder. Ambiguous jury instructions given by judges during the 1980s have resulted in numerous capital cases being overturned and remanded for new sentencing hearings.
The District Attorney's Office has resolved many of those cases through new guilty-plea agreements or, as in the case of Mumia Abu-Jamal, deciding to abandon the death penalty and accept life sentences.
Tasha Jamerson, spokeswoman for District Attorney Seth Williams, said the office had no immediate comment on the Williams case.
Nolan said the District Attorney's Office must respond to his petition by Sept. 21. The emergency appeal has been assigned to Common Pleas Court Judge M. Teresa Sarmina to decide whether to block the Oct. 3 execution.
The Norwood murder shocked many people, in large part because of how Norwood's body was found.
Norwood was last seen leaving his Mount Airy home on June 11, 1984, to do volunteer work at St. Luke's Episcopal Church in Germantown.
Four days later, a boy walking his dog found Norwood's charred body propped against a gravestone in Ivy Hill Cemetery in West Oak Lane. He had been beaten to death with a tire iron.
A month later, police charged Draper, 18, son of a police Civil Affairs Unit officer. Draper, in turn, implicated Williams in the killing, which he said began as a robbery.
That was just the start. Draper also told police that Williams admitted to him that on Jan. 26, 1984, he had stabbed to death Herbert Hamilton, 50, after Hamilton made sexual advances.
Hamilton's nude body, beaten and stabbed, had been found in his West Philadelphia apartment.
Williams' friends and associates were shocked at the allegations against a young man who overcame an abusive childhood to excel as a Germantown High School quarterback and go on to Cheyney University.
Draper became the key prosecution witness against Williams in both killings.
Williams was convicted of third-degree murder in Hamilton's death in February 1985 after the jury believed his self-defense claim and evidence of Hamilton's homosexuality.
A year later, Williams was convicted of first-degree murder in Norwood's killing and sentenced to death.
Draper pleaded guilty to second-degree murder in Norwood's death and was sentenced to life in prison without parole. Now 46, Draper is at the state prison in Frackville, Schuylkill County.
Whether Williams' latest petition is enough to halt his execution is unclear. Just three people have been executed since Pennsylvania reenacted the death penalty in 1978 - two in 1995, the last in 1999 - and only because all three ended their appeals and asked for death.
Marc Bookman, executive director of the Philadelphia-based nonprofit Atlantic Center for Capital Representation, urged the District Attorney's Office to take a new look at the case.
"We're hopeful that the D.A.'s Office will take a very careful look at this case," Bookman added. "It appears that Terry Williams suffered very horrible sex abuse throughout his lifetime, and the crimes that he committed were as a very young person, barely 18 and 17."
Contact Joseph A. Slobodzian at 215-854-2985, email@example.com, or @joeslobo on Twitter.