What's not clear is exactly how the journalist was killed. While authorities said that Salazar died in an accidental shooting, others say he was murdered. And now four decades later, the answer might finally be coming to light.
It was one of the largest anti-war protests of the Vietnam War era. On August 29, 1970, an estimated 30,000 demonstrators marched through East Los Angeles as part of the National Chicano Moratorium Against the Vietnam War.
As the crowd approached Laguna Park, hundreds of officers in riot gear clashed with demonstrators. Fires were set and dozens were arrested.
Ruben Salazar was covering the event as news director for KMEX. Salazar was killed inside the Silver Dollar Cafe. Authorities say the 42-year-old was hit in the head at close range by a tear gas canister that had been fired by an L.A. County Sheriff's deputy. But others think Salazar had been targeted.
"Ruben, unfortunately, fell into a plan that I believe was organized by persons unknown within the sheriff's department, where he stood no chance," said Raul Ruiz, a professor at California State University-Northridge.
Ruiz was editor of La Raza newspaper. He took photos on that fateful day.
"It was an extraordinary amount of firepower directed at this little bar in East L.A.," said Ruiz.
Sheriff's deputies later testified that they were responding to reports of an armed man entering the Silver Dollar Cafe. But Ruiz and many others feel that Salazar was silenced due to his status as a prominent journalist.
"Deputies did wrong at the Silver Dollar, and I believe a crime was committed," said Ruiz.
And now, 40 years after Salazar's death, the L.A. County Sheriff's Dept. has agreed to release several boxes of documents and photographs pertaining to the investigation into Salazar's death, which had been ruled a tragic accident.
"The sheriff says, 'We have nothing to hide. I want to let the public know what happened 40 years ago,'" said L.A. County Sheriff's Spokesman Steve Whitmore.
The documents have been turned over to the County of Los Angeles Office of Independent Review.
"They are unbiased, and they are going to report as to what is contained in those boxes without fear, favor or prejudice," said Whitmore.
Ruiz, who considered Salazar a good friend, said he's hoping someone will reopen a criminal investigation.
"Let a jury decide whether or not it was accidental or justifiable homicide, or in fact a homicide," said Ruiz. "I, quite frankly, believe it was a homicide."
In the years after his death, Salazar became a hero in the Chicano movement, considered by many to a martyr.
In Boyle Heights, playwright Rene Rodriguez is staging his fictional account of what happened inside the Silver Dollar Cafe on that day.
"All of a sudden they were thrust into history. They didn't even want to be thrust into history, but it just so happened that that's what happened," said Rodriguez.
A 40th anniversary commemorative march is scheduled for Saturday at 9 a.m. at Belvedere Park, continuing to what was once the Silver Dollar Café, ending at what was once Laguna Park, now called Ruben F. Salazar Park.