By Doug Dunbar, CBS 11 News

DALLAS (CBSDFW.COM) – Monday marks the 47th anniversary of the JFK assassination in Dallas.  It also brings yet another book about that fateful day.  But, this one is different.  It comes from the perspective of two men who were on Kennedy’s Secret Service detail that day.

One of those men is Clint Hill.  He’s the agent who was first to reach the President and First Lady.  47 years later, the image of what happened is as clear as that day in Dealey Plaza.

“That’s when I saw him grab at his throat, and when that happened, I jumped from the car and began to run,” Clint Hill says remembering that day.  As the world knows from the video, it was Clint Hill who ran desperately trying to reach the First Lady who he was assigned to protect.  What he can’t get over is the moment when he finally reached her.

“So, you literally think when she reached over the back in that dramatic moment, it was to go after a piece of her husband,” CBS11’s Doug Dunbar asked?  “She was trying to reach something that came off the President’s head,” Hill said.

In the seconds between what many believe was three shots fired allegedly by Lee Harvey Oswald from the sixth floor of the Texas School Book Depository, Clint Hill went numb.  It was duty first, despite the horror that unfolded with the third shot which hit just inches from where he was.

“Just before I got to the Presidential car, the third shot rang out,” Hill said.  “I heard it, and I felt what happened because when it the President’s head, it opened up a wound in the upper right rear of the head right above the ear.  Blood and brain matter spewed out, and it covered the car and myself. I finally got up on the trunk, tried to assist her into the seat, and at that point, the President slumped to his left onto her lap.  His face was up to the right.  His eyes were fixed.

Fast forward to Parkland Hospital, and Hill says the First Lady would not let go of her husband until Hill made one move.

“I took my coat off and placed it over his head and upper torso,” Hill remembered.  “When I did that, she just let go, and we picked him up and put him on the gurney.”

In less than 20 minutes, the world had changed.  Clint Hill’s life would never be the same.

“It was my responsibility to protect the President, and I was the only one that had the chance to do anything, and I failed in being able to do that,” he said.  “That’s why I feel the sense of guilt and responsibility.”

In the years that followed, those graphic images made for haunting dreams.  But, time did not heal.  After retiring in 1975, Hill spiraled into depression and alcoholism.

“I just lost myself because that was the best way I could handle it…just drink and fall asleep and try to not have the nightmares I was having,” he said.

47-years later, Hill and fellow retired agent Gerald Blaine know their time is growing short – in life, and in respect to what they call ‘setting the record straight’.

“Unless somebody spoke up and filled in the gaps, that was going to be the way history was written, and that would be a tragedy,” Blaine said.

“There were 3 shots, and they all came from the same location,” Hill remembered.  “Our right rear, which puts them right up in that building.  There were no more than three, and there was only one shooter.”

If there is one regret for Clint Hill, who continued to protect Jacqueline Kennedy for a year after the assassination, it would be that despite what he called a close working relationship, they never once talked about what happened that day in Dallas.

“I probably should’ve told her how sorry I was, but I never did,” he said.  “I think she knew.  I think she could see it.”

As we know, Lee Harvey Oswald would never be tried in the assassination of President Kennedy.  He was killed by Jack Ruby just two days later.