There was something missing when John F. Kennedy was buried at Arlington National Cemetery — namely, his brain.

In a decidedly less high-tech era, JFK’s brain was placed in a stainless-steel container with a screw-top lid during the autopsy at Bethesda Naval Hospital.

“For a time, the steel container was stored in a file cabinet in the office of the Secret Service,” writes James Swanson, author of the upcoming book, “End of Days: The Assassination of John F. Kennedy.”

The brain was eventually stored in a locker with other medical evidence and taken to the National Archives, where it was “placed in a secure room designated for the use of JFK’s devoted former secretary, Evelyn Lincoln, while she organized his presidential papers.”

But in October 1966, it was discovered that the brain, the tissue slides and other autopsy materials were missing, reports The New York Post.

A probe was launched at the time, yet the investigation failed to uncover the fate of the missing brain. To this day, the brain remains unaccounted for.

But the initial inquiry did “uncover compelling evidence suggesting that former Attorney General Robert Kennedy, aided by his assistant Angie Novello, had stolen the locker,” says Swanson.

And while the premise of the attorney general swiping his brother’s brain may sound like the farfetched journalism of a fanciful sensationalist, Swanson has legitimate chops. He is an attorney who has written about history, the Constitution, popular culture, and other subjects for publications like the Wall Street Journal, Smithsonian and the Los Angeles Times. He is also the author of the New York Times bestseller, “Manhunt: The 12-Day Chase for Lincoln's Killer.”

So is Swanson in agreement with the conspiracy theorists, who say that the brain was stolen to conceal crucial evidence of the assassination?

“My conclusion is that Robert Kennedy did take his brother’s brain — not to conceal evidence of a conspiracy but perhaps to conceal evidence of the true extent of President Kennedy’s illnesses, or perhaps to conceal evidence of the number of medications that President Kennedy was taking,” he said.

Related stories on MNN: