The conspiracy theories are endless. They seem to multiply like locusts.

A classic whodunit: Was it the Mafia? How about Fidel Castro and Cuba? Maybe LBJ himself was the mastermind? What about the CIA? J. Edgar Hoover and the FBI? Could it have been Nikita Khrushchev and the Soviet Union?

Just who really was involved in the assassination of President John F. Kennedy? That question has fascinated Americans for 50 years.

Could the assailant really have been a pathetic, underachieving simpleton named Lee Harvey Oswald all by himself?

“Nobody wants to believe that these two losers could impact the world the way they did,” suggested Hugh Aynesworth, a former Dallas Morning News writer and author of the recently released book “November 22, 1963: Witness to History.”

Aynesworth, now 82, was referring to Oswald and Jack Ruby, the man who shot Oswald. To paraphrase pop artist Andy Warhol, both wanted their 15 minutes of fame, Aynesworth believes.

He’s right. Many observers expect a more complicated plot in the Kennedy assassination. They are reaching for something more mysterious and potent that validates such a tragedy. Surely, two grandstanding clowns can’t be all there is. Even U.S. Secretary of State John Kerry opened a Pandora’s box, recently telling NBC’s Tom Brokaw, “To this day, I have serious doubts that Lee Harvey Oswald acted alone.”

Aynesworth subscribes to the theory that Oswald, indeed, was alone. “I have seen absolutely no evidence to the contrary,” Aynesworth maintained during a telephone conversation. “Look, I’m aware that probably 75 percent of Americans believe in conspiracy theories about Kennedy. The movies, documentaries and television shows all predict conspiracies. Oliver Stone’s movie (titled “JFK”) probably influenced two generations of Americans. But the only thing that was right in that movie was the date and the city.”

Aynesworth’s claim to fame is that he witnessed the JFK assassination, the subsequent capture of Oswald and the Ruby shooting incident. It was an unfathomable time when Aynesworth originally was supposed to have been enjoying a day off on that Friday, Nov. 22. That off-day suddenly became a media maelstrom.

“Oswald wanted to be somebody,” Aynesworth explained. “He wanted to be above the fold. He wanted to show he was bigger and better than everyone else — somebody who couldn’t quite make it in life and wanted to go out with a bang.”

Aynesworth knew Ruby in those days. Ruby often would frequent the Morning News to buy ad space to promote his seedy strip club, then talk to the newspaper’s writers seeking more publicity while there. All in the name of trying to make a name for himself, Aynesworth recalled. “He was a loudmouth show-off,” Aynesworth blurted.

He believes the impetuous Ruby just wanted to be known as the guy who killed The Guy who killed President Kennedy. As if he was doing everyone a favor for killing the Most Hated Person in America that fateful November day. A great “American hero.” Yeah, right. More like an outlandish, self-promoting Don King-type before there was even a Don King.

Except many Americans were angry with Ruby. “Because they wanted Oswald to live to answer the question — why?” Aynesworth said.

Aynesworth, then the Morning News’ aviation and aerospace reporter, had his Nov. 22 all planned that eventful day. A little early lunch, then watch the Kennedy motorcade in the afternoon before heading to Southern Methodist University to take in a lecture by a space scientist.

However, shots were fired at the president and Aynesworth’s day changed ... the rest is history.

And Dallas for decades was excoriated as that Haunted City that killed the King of Camelot.

But with time comes the power of healing. Aynesworth says the NFL and pop culture lent a helping hand in a big city’s long, arduous comeback story.

“The Dallas Cowboys and the television show ‘Dallas’ helped cool the climate here a little bit,” he said.

The Cowboys, of course, ultimately performed with the moniker “America’s Team,” and “Dallas” arguably became television’s most popular prime-time show of the late 1970s and early ’80s.

Now, Aynesworth is a man in demand. A panel discussion about the Kennedy assassination one day. A special reunion dinner for the media members who covered Nov. 22, 1963, on another day. A television show appearance is stamped on his schedule; a book party follows that; daily telephone calls from people like me. So, it’s on and on in 2013.

Says Aynesworth, with a touch of wistfulness: “I’m getting too old for this.”

But he admits the excitement is unforgettable.

“I’m surprised by the international interest in this,” Aynesworth mused. “I’ve been getting calls from Argentina, Paris, London, Oslo, Turkey ...”

The list goes on ... and so does Aynesworth, who 50 years ago covered an event for the ages — on his day off.

Gregory Clay is assistant sports editor for McClatchy-Tribune News Service.