SALT LAKE CITY (AP) -- Labor activist and songwriter Joe Hill is revered by many as a hero and martyr. To others, Hill was a murderer who gunned down a Salt Lake City grocer and his son and got what he deserved when he was executed by firing squad in 1915.

Ahead of the 100th anniversary of his death in November, admirers of the Swedish-born immigrant will gather in Salt Lake City this Labor Day weekend to celebrate his life with music and speeches.

"He started the struggle that we still fight today," said Dale Cox, president of the AFL-CIO in Utah. "What he worked on and what he died for is workers' rights. That's what his whole life was centered around."

Living family members of grocer John Morrison and his son J. Arling Morrison - the two men who Hill was convicted of killing - won't be joining the celebration. They recognize Hill may have been convicted on circumstantial evidence, but said they're tired of the hero worship.

"I believe he was a murderer," said Michael Morrison, the 66-year-old grandson of John Morrison. "It doesn't matter what you say, you're not going to change my mind."

The looming centennial of Hill's execution has rekindled interest in a story that featured a well-known union organizer in Hill, a respected family in the Morrisons and remains, to many, an unsolved whodunit.

The Salt Lake Tribune, the state's largest newspaper, recently published a package of stories, photos and videos about Hill's legacy and what became of the descendants of the Morrison family. (http://bit.ly/1JR5Xml )

In Utah, Hill's story is fairly well known. Outside of Utah, he's probably best known for being the subject of a poem turned into a song that Pete Seeger made famous in the 1960s called "I Dreamed I Saw Joe Hill Last Night."

"They framed you on a murder charge," croons Seeger in the song, "Says Joe, but I ain't dead."

The song was famously performed by Joan Baez at Woodstock and in more recent years by Bruce Springsteen and guitarist Tom Morello of the rock band Rage Against the Machine. When Baez sang the song in the early 1970s in Salt Lake City, Michael Morrison said his cousin John Arling Morrison heckled the famous folk singer by repeatedly yelling, "He's a murderer."

At Saturday's event in Salt Lake City - held in the Sugar House neighborhood where Hill was executed - singer Judy Collins is scheduled to headline a daylong concert where Hill's music and writings will be featured.

One of his most famous songs is the "The Preacher and the Slave," a ballad where the oft-used phrase "pie in the sky" was created.

"Work and pray, live on hay; you'll get pie in the sky when you die," the lyrics say. "Working men of all countries unite. Side by side, for freedom we will fight."

Hill became the lead suspect in the 1914 double murder because he was treated by doctors the same night for a gunshot wound to the chest. Prosecutors used that as evidence linking him to the killings. Hill reportedly told doctors that he was shot by a jealous friend in a quarrel over a woman, but he didn't present that alibi at trial.

Lori Taylor, a historian and one of the organizers of Saturday's concert, said new evidence uncovered by author William Adler in a book published in 2011 cements Hill's innocence. Hill was assumed to be guilty because police of that era considered members of the Industrial Workers of the World union to be radical criminals, Taylor said. No motive was given by police.

Prior to his execution, Hill sent a telegram to a fellow labor leader that became a rally cry for supporters: "I die like a true blue rebel. Don't waste any time mourning. Organize."

Michael Morrison said sympathizers were intent on making him a martyr and hero after the execution and ignored inconvenient details that would blemish that image. His father, Merlin Morrison, was also in the store that night as a young man and recounted how the killers came in to the grocery store and said, "We got ya now" and shot John Morrison in the back. Police believed the other man fled, never to be found. The events troubled Merlin Morrison until he died in 1983, Michael Morrison said.

Taylor and Cox said this weekend's salute of Hill isn't so much about proclaiming his innocence but honoring a message that is still relevant today.

"His songs captured people's imagination because they had a little bit of satire, a little bit of humor and were a bit biting about the issues of his day, like inequality," Taylor said. "They still resonate."