04/05/2012 10:09 am ET Updated Apr 05, 2012

Secret Service Agent, Clint Hill, Describes JFK Assassination In New Memoir 'Mrs. Kennedy And Me'

In Clint Hill's new book, 'Mrs. Kennedy and Me: An Intimate Memoir,' Hill reveals gruesome details of the day John F. Kennedy was assassinated.

The most chilling detail recounts Jackie Kennedy jumping onto the back of the car in order to retrieve a piece of the President's skull. Hill notes, "Her eyes were filled with terror...She was reaching for something. She was reaching for a piece of the President's head."

Hill was a first-hand witness of the assassination, as he was Jackie Kennedy's secret service agent. He was standing on the follow-up Secret Service vehicle's running board in Dallas, Texas when Kennedy was shot first in the neck, then in the head.

Hill recounts that suddenly, he saw the President grab for his throat. "Somebody had fired a shot at the President, and I had to get myself between the shooter and the President and Mrs. Kennedy. Nothing else mattered," he notes in the book.

Hill's initial thought after the shooting, taking the First Lady in his arms, was, "How did I let this happen to her?"

Hill was formerly a Secret Service agent for President Eisenhower. In a way, moving to the First Lady was a bit of a demotion. However, the pair grew extremely close. They sneaked cigarettes together, and he even offered her advice when she admitted she was scared for her safety before the Dallas trip. Though Hill denied it in an interview with People magazine, USA Today writes that "it's clear from his book that Hill (who was married) loved her."

If you want to read about the number of alleged affairs that JFK had, you'll have to look elsewhere. Though Hill's book recalls the assassination in gory detail, he remains mute on the scandals that rocked the Kennedy family. The book world isn't short on these types of books though. Earlier this year, JFK's former intern wrote her own memoir about an alleged affair with the former president.

CORRECTION: This article formerly stated that Hill was walking alongside JFK's car. This has been changed to: "He was standing on the follow-up Secret Service vehicle's running board."