On the 50th anniversary of the day in 1964 when the Warren Commission delivered its still-controversial findings about JFK's assassination to President Lyndon Johnson, LIFE.com presents the story of how editor Richard Stolley flew to Dallas from Los Angeles within hours of the murder; how he tracked down a 58-year-old amateur-film buff named Abraham Zapruder; how he purchased Zapruder's home movie of the assassination for LIFE magazine—and what all of that ultimately came to mean for LIFE, for Zapruder, for Stolley himself and for the nation, then and now.
[Watch a video about Stolley's grim adventures in Dallas]
It's unlikely that any 26 seconds of celluloid have ever been discussed and dissected as thoroughly as the chilling scene that Zapruder captured that day in Dallas, in a movie known ever after as "the Zapruder film." The jittery color sequence showing JFK's motorcade moving through the sunlit Dallas streets—leading up to the utterly shocking instant when a rifle bullet slams into the president's head—is still, five decades later, one of the 20th century's indispensable historical records.
Having flown from L.A. that afternoon, Stolley was in his hotel in Dallas just hours after the president was shot. "I got a phone call from a LIFE freelancer in Dallas named Patsy Swank," Stolley recently told TIME producer Vaughn Wallace, "and the news she had was absolutely electrifying. She said that a businessman had taken an eight-millimeter camera out to Dealey Plaza and photographed the assassination. I said, 'What's his name?' She said, '[The reporter who told her the news] didn't spell it out, but I'll tell you how he pronounced it. It was Zapruder.'
"I picked up the Dallas phone book and literally ran my finger down the Z's, and it jumped out at me—the name spelled exactly the way Patsy had pronounced it. Zapruder, comma, Abraham."