Dead for 87 years after being executed by Pennsylvania for a murder he likely did not commit, Alexander McClay Williams finally received his headstone Saturday, his grave in an abandoned Delaware County cemetery unmarked no more.

The 100-pound black-granite rectangle cost $850 — paid for in four days with a GoFundMe site — and was placed in moist soil beneath the bent branch of an ash tree.

Williams' grave was one of the only mowed patches in the untended cemetery, where gray and weathered tombstones were nearly swallowed by the jungly tangles and chaotic disarray of weeds that covered the long-deceased in what used to be known as Green Lawn Cemetery in Chester Township.

Though family and guests who positioned Williams' slab had to guess where his head might have been laid, they hoped his soul was somehow resting easier now that his final whereabouts were revealed.

In white letters chiseled onto a polished surface that mirrors a mourner's face, the headstone reads:

Alexander McClay Williams

July 23, 1914 — June 8, 1931

Executed for a crime he did not commit.

"Justice deferred is justice denied"

"To live in the hearts of those we leave behind is not to die," said Samuel Lemon, a Neumann University administrator who spent more than 30 years collecting evidence he hopes will fully exonerate Williams, a 16-year-old African American youth who was executed for allegedly stabbing a white woman 47 times with an ice pick in October 1930.

Twenty-five people who came to honor Williams bowed their heads. They sang. They prayed.

They invoked the name of Trayvon Martin, the unarmed 17-year-old African American shot dead in his Florida town in 2012.

"I am woke," said Oceola Perdue, 50, a public relations executive for Boscov's from Newark, Del., and Williams' niece, announcing her social awareness, and linking her uncle to the endless roster of black men unjustifiably accused of crime, or themselves the victims of racially motivated murders.

"I want to see justice for my uncle and any other African Americans treated wrongfully by the state."

READ MORE: Lawyer: Some justice for teen executed 86 years ago

Justice was in short supply back in 1930, when Vida Robare, matron at the Glen Mills School for Boys in Delaware County, was stabbed over and over with an ice pick, with two of her ribs broken and her skull fractured.

Williams, who stood 4-foot-7 and weighed 91 pounds, was a troubled, learning-disabled kid from a family of 13 children who grew up in Cheyney, said Lemon.

The son of an illiterate mushroom worker, Williams had been sent to the boys' school in 1926 for setting fire to a barn, said Lemon, of Media, whose great-grandfather William Ridley was Williams' defense attorney, the first African American lawyer admitted to the Delaware County bar.

Under police interrogation, Williams confessed to the murder, "but he was coerced into saying he did it, and was railroaded," said Lemon.

Even at the time of the killing, people doubted a child could manage it.

"This crime was committed by a full-grown and strong man," said Chief County Detective Oliver N. Smith the day after the slaying, according to an article in the Chester Times. "The woman was unmistakably athletic and could have fought off a boy."

Lemon, who has a Ph.D. from the University of Pennsylvania in education, culture, and society, pointed out that Robare's ex-husband, Fred, was the likely murderer — the last person to see her alive and the first to discover her body. The 47 stabbings implied passion, he said.

"This was extreme domestic violence portrayed as a race crime," said Lemon, who has spoken to Robare's family members. They themselves don't believe Williams was the killer, he said.

Authorities apparently doctored the death certificate to make it seem as if Williams was responsible, said Lemon. An inarticulate black teenager didn't stand a chance against an aggrieved white hierarchy fueled by race hate and hungry for a fall guy.

Believed to be the youngest person to be sent to the electric chair by the Commonwealth of Pennsylvania, Williams was executed on June 8, 1931 at Rockville Prison in Bellefonte, Centre County.

With the help of attorney Robert Keller, Lemon was able to present the inconsistencies in Williams' case to the Delaware County courts, and Williams' criminal record was expunged last year.

But Lemon isn't done.

He wants the Pennsylvania Supreme Court to have Williams' conviction vacated. "I don't want just a pardon," said Lemon. "That's still an admission of guilt."

Asked what motivates him, Lemon said simply: "I'm a Quaker and we have leadings — things we feel strongly obligated to do. I never felt a choice to exonerate Alexander Williams. It's an obligation, a task I can't say no to."

At the headstone ceremony Saturday, Lemon led the group in the gospel song "Down by the Riverside" under a blue sky.

As Williams' sister, Susie Carter, 88, lent her voice, the gathering got louder singing the lyrics "I'm gonna lay down my heavy load, down by the riverside."

When they were done, Lemon said to everyone, "This is a special day."

Still, his Quaker leadings took hold soon after, and he couldn't help adding:

"But this is not over."