CHICAGO (CBS) — Fifty years after he witnessed the assassination of his friend and mentor, Dr. Martin Luther King Jr., the pain is still raw for Rev. Jesse Jackson Sr.

In April 1968, Jackson was only 24 years old, living in Chicago, when he and other King aides were summoned to the civil rights leader’s home in Atlanta.

King was in a grave mood, under attack for criticizing the war in Vietnam, and even taking heat from other African American leaders.

Jackson said King told them he’d been suffering a migraine for three days.

“’Maybe I could just quit. Maybe I’ve done as much as I can do in 13 years,’” he recalled King telling him. “’Maybe I could just fast to the point of death.’”

First, however, King went to Memphis to rally support for striking sanitation workers. Jackson said King was in no mood to speak on the night of April 3, but found the energy to give what turned out to be his last speech.

“I’m not fearing any man, Mine eyes have seen the glory of the coming of the Lord,” King said.

What captured Jackson’s attention was the sight of other ministers crying.

“Ministers and funeral directors don’t cry very much,” he said.

The next day, April 4, at the Lorraine Motel, King teased Jackson about his casual attire before dinner.

“I said ‘Doc, the prerequisite for eating is appetite, not attire.’ He said, ‘You crazy.’ He laughed,” Jackson said.

Moments later, as King, Jackson, and others stood on the balcony, King was felled by an assassin’s bullet.

“Pow. He raised up. Bullet hit him in the center of his tie, and he backed against the wall, and he was just out of it,” Jackson said.

When he saw his friend and mentor bleeding to death, Jackson was “traumatized.”

“I was full of pain, and anger, and sorrow, and desperation, and many emotions at the same time,” he said.

Just after King’s assassination, Jackson told reporters, “To some extent, Dr. King has been a buffer for the last few years between the white community and the black community. The white people do not know it, but the white people’s best friend is dead.”

Fifty years later, Jackson said the pain is still raw.

“Every time the scab comes off, the wound is fresh again,” he said.

However, King’s death did not diminish Jackson’s resolve to carry on the fight for civil rights.

“We cannot let one bullet kill the whole movement,” he said. “If you play in the big game, and the best player gets hurt, you can’t forfeit the game. You can’t run away. You’ve got to keep fighting.”

Jackson said he’s certain King would mourn the level of poverty in the United States today.