Mr. SPECTER. What did you observe as to President Kennedy's condition on arrival at the hospital?

Mr. HILL. The right rear portion of his head was missing. It was lying in the rear seat of the car. His brain was exposed. There was blood and bits of brain all over the entire rear portion of the car. Mrs. Kennedy was completely covered with blood. There was so much blood you could not tell if there had been any other wound or not, except for the one large gaping wound in the right rear portion of the head.

https://www.wnd.com/2013/10/rare-zapruder-footage-multiple-jfk-assassins/

'The impact was like the sound of something hard hitting a melon shattering into cement

"In the same instant, blood, brain matter and bone fragments exploded from the back of the President's head... and splattered all over me - on my face, my clothes, in my hair."

“As I peered into the backseat of the car,” Hill recalled. “I saw the president’s head in [Jackie’s] lap. His eyes were fixed, and I could see inside the back of his head. I could see inside the back of the president’s head.”