A Secret Service agent who tried to shield former President John F. Kennedy from an assassin’s gunfire in 1963 died on Monday.

Clint Hill, 93, died at his California home from unknown causes. He had been serving on presidential security detail for just three years when he made the move that defined his career.

On a fateful November day, Hill scrambled to protect Kennedy and his wife, Jacqueline, as they enjoyed an open motorcade tour through Dallas.

As shots rang out, the 31-year-old agent threw himself onto the back of Kennedy’s limousine in an attempt to protect the first family from danger. He pushed Jacqueline, who had crawled onto the trunk of the vehicle to collect bits of her husband’s head blown off by the assassin’s bullet, back into the limousine and covered the first couple’s bodies as the limousine sped to the nearest hospital. 

“Thought swirled in my head,” Hill remembered in his 2012 memoir, Mrs. Kennedy and Me, that reflected on the assassination. “‘Will we get there in time? Go faster, go faster. He’s not breathing. Hang on, Mr. President, hang on.”

“And then the thought that haunts me still, how did I let this happen to her?” he wrote.

Hill was specifically assigned to Jacqueline’s security detail and grew to have a close relationship with the then-first lady. While his actions caught the nation’s eye and earned him accolades of bravery, that November day, and for decades afterward, he was tortured by the belief that he could have prevented her husband’s death.

Hill was promoted following the assassination, eventually becoming an assistant director of the Secret Service. But in 1975, he resigned from the Secret Service a broken man, still shattered over the Texas calamity.

“My dad drilled into me that when you’re given an assignment to do, you do it ’till it’s fully finished,” the former agent said during a CBS interview last year. “I had an assignment to keep the president and Mrs. Kennedy alive. I only kept one of them alive. One died on my watch.”

While the congressional Warren Commission concluded that Lee Harvey Oswald acted alone to assassinate Kennedy on Nov. 22, 1963, some details surrounding the shocking murder remain disputed, sparking speculation, including from some members of the Kennedy family, as to what happened.

President Donald Trump made headlines after he assumed office for the second time in January for releasing thousands of previously classified files on the assassination to the public.

TRUMP TURNS TO FORMER CRITICS TO HELP BUILD OUT SECOND ADMINISTRATION

“That’s a big one,” Trump said as he signed the executive order declassifying the files. “Lot of people are waiting for this a long, for years, for decades. All will be revealed.”

There are still approximately 500 documents related to the Kennedy assassination that experts believe Trump will not be able to release.