After the shooting in Dallas, President Kennedy's body was flown to Washington and taken to the Bethesda Naval Hospital for a full autopsy.
His brain was put in a stainless steel container with a screw top lid, which was then stored at a Secret Service facility.
Keeping it in the family: A new book alleges that Robert Kennedy (left) took the case that contained his brother Jack's (right) brain after he was shot and killed
The aftermath: President Kennedy was shot in Dallas and his assassination was the subject of several investigations and inquiries but there is no officials word on where the slain president's brain is now
At some point, that steel container was put inside a footlocker and then transported to the National Archives.
Author James Swanson, who wrote End Of Days: The Assassination Of John F. Kennedy, told The New York Post that 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.'
'In October 1966, it was discovered that the brain, the tissue slides and other autopsy materials were missing — and they have never been seen since,' Swanson said. His investigation led him to believe that then-Attorney General Robert Kennedy took the brain with the help of his secretary.
In mourning: Robert Kennedy stood at Jacqueline during her husband's funeral
It was only revealed years after the President's death that he had suffered from Addison's Disease for much of his adult life.
The potentially-fatal disease occurs when a person's body produces insufficient hormones, and as such the treatment involves a number of replacement hormones being supplemented to the system through medication.
He was also diagnosed with hyperthyroidism and had severe back pain, making it unsurprising that he had a steady stream of medication prescribed to him by one of three doctors during his presidency. This book is one of many that are being released prior to the 50th anniversary of President Kennedy's death on November 22, 1963.
Additional Info; These are pictures of either JFK's back brace, or him wearing it.