
It is dark and logical, really. Jackie Kennedy reached her arm across the limousine trunk in frame 313 of the Zapruder film. She grabbed hold of a piece of brain tissue and skull from her husband. That is what agent Clint Hill of the Secret Service saw. The film makes that point clear.

People have a really remarkable instinct. She decided not to bolt in order of escape. She walked toward the risk. Her pink suit bore blood stains. Head of the president had exploded against her. Still, she went out there anyway.
Clint Hill shot after the car. He watched her hand reach forward. He jumped onto the back of the limousine accelerating. He pushed her back into the chair. She had absolutely no awareness of her own behavior. Instinct drove the path. Like an animal protecting its mate.
The piece of skull was dark against the bright trunk. Some said it was a rose pin at first. It wasn’t. That was part of the head of the president. She held it all the way to Parkland Hospital. She wouldn’t let go. The nurses had to pry it from her hand.

In the hospital, she stood there in her blood-stained suit. She wouldn’t change. “Let them see what they’ve done,” she said. The suit still exists. They locked it away. It will stay locked up until 2103.