at Dealey Plaza
Gary Mack, a Dallas broadcaster whose fascination with the Kennedy assassination led him to become a widely consulted expert on the event and, eventually, the curator of the Sixth Floor Museum, which is devoted to the assassination, died on Wednesday in Arlington, Tex. He was 68.
The museum said on its website that he had died after a long illness. The Dallas Morning News reported that his wife, Karin Strohbeck, said the cause was a rare and aggressive cancer.
Mr. Mack, like many Americans of his generation, stayed glued to the television set as the events of November 1963 unfolded. His interest was rekindled after seeing the Zapruder film footage of the assassination on television in 1975.
Interest became obsession when he began working in 1981 as an announcer, cameraman and news producer at KXAS-TV, a local NBC station, where part of his job was to manage and preserve the station’s film archives and its coverage of the assassination and its aftermath.
As he pored over the historical record, read every account of the assassination he could lay his hands on and inspected the footage frame by frame, he developed an impressive command of the subject.
Mr. Mack became a valued resource for historians and documentary producers. He was a consultant for the Discovery Channel, the History Channel and National Geographic Channel and a producer of the documentaries “J.F.K.: The Dallas Tapes” and “J.F.K.: Breaking the News,” about television coverage of the assassination.
“We’re not going to have one person that knows that much about the assassination, and all elements and all roads leading everywhere,” Hugh Aynesworth, a former reporter for The Dallas Morning News told KERA, the local public television station. “Gary was the man.”
Mr. Mack was born Lawrence Alan Dunkel on July 29, 1946, in Oak Park, Ill. After earning a degree in journalism from Arizona State University in 1969, he worked at a variety of AM and FM radio stations as a disc jockey, music director and program director. Looking for a catchier on-air name, he came up with Gary Mack.
In Dallas, he first became known as a Kennedy assassination conspiracy theorist, with some eye-catching finds to his credit. In the 1970s, he discovered that a Dallas police officer on duty on Nov. 22, 1963, had left the microphone on his radio switched on, and that the audio material had been transferred to tape at Police Headquarters.
The background sounds on the tape, which Mr. Mack obtained from a retired police officer, suggested to him that a fourth shot had been fired by a second gunman from the grassy knoll.
That theory, which members of the House Select Committee on Assassinations found persuasive, was discounted by researchers at the National Academy of Sciences, who concluded that the popping sounds were electronic noise, a finding that Mr. Mack accepted only grudgingly.
“He started out as a pretty vicious conspiracy theorist when he was with Channel 5,” Mr. Aynesworth, who witnessed the assassination and the ensuing events, told The Dallas Morning News in 2013. “Gary made some pretty ridiculous claims.”
At the same time, Mr. Mack proved to be a skilled debunker. In the early 1990s, working with Dave Perry, a former insurance investigator, he conclusively rebutted the contention of Ricky Don White that his father, Roscoe, a Dallas police officer, had fired on Kennedy from the grassy knoll as part of a wider conspiracy.
Over time, he adopted a much more measured view of the assassination.
“I had learned the basics — step back and look at all sides,” he told The Dallas Morning News, referring to his journalistic training. “But I’d read all the pro-conspiracy books and was convinced they were probably right. When I decided to step back, I realized they weren’t telling me the whole story, just one side of it.”
He eventually settled on what might be called conspiracy lite. That is, he doubted that Lee Harvey Oswald acted alone, and believed, at least, that there was more to the Oswald story than we know, but shed the more lurid hypotheses in favor of scientific detachment.
In 1989, he helped the museum develop its opening exhibition, “John F. Kennedy and the Memory of a Nation,” still on display in an updated version. The museum is in the former Texas School Book Depository in Dealey Plaza, where Oswald fired on the presidential motorcade.
In 1994, he joined the museum as an archivist and expanded its collections. He added 250 hours of television news coverage of the assassination, most of it from the archives of local television stations, and persuaded many eyewitnesses to donate photographs and film.
Most recently, he obtained eight-millimeter film from Tina Towner Pender, who as a 13-year-old stood near the motorcade just seconds before shots were fired, and still photographs taken by her father, Jim Towner, who was standing with her.
In addition to his wife, Mr. Mack is survived by a son, Stephen Dunkel; a sister, Susan Coleman; and two grandchildren.
The mystique of the assassination and the unsolved questions surrounding it held him in a tight grip. “I’m personally convinced there’s more than just Oswald involved, but I can’t prove it and neither can anyone else,” he told The Dallas Morning News. He added, “It’s much more fun to believe in a conspiracy.”