Civil rights leader Andrew Young (L) and others on balcony of Lorraine motel pointing in direction of assailant after assassination of Dr. Martin Luther King, Jr., who is lying mortally wounded at their feet. Joseph Louw—The LIFE Images Collection/Getty Images

He was the only photographer there.

On April 4, 1968, photographer Joseph Louw was on the road in Memphis with Dr. Martin Luther King Jr. for a public television documentary he was working on. He had ended his dinner early to catch the Huntley-Brinkley Report in his motel room, a few doors down from Dr. King’s. When he turned on the TV, Martin Luther King Jr. came on screen. It was footage from the “I’ve Been to the Mountaintop speech” Dr. King had delivered the night before, in which he said that he was ready to die.

Louw, from South Africa, had graduated from Columbia University the year prior and worked for the Public Broadcasting Laboratory, an experimental public television series created by National Educational Television (NET) in New York City. PBL sought to explore topics that commercial television didn’t and began work on its documentary about Dr. King in January of 1968. Louw was following Dr. King and the Southern Christian Leadership Conference (SCLC) as they organized the Poor People’s Campaign.

When the news broadcast ended, a loud noise jolted Louw. He rushed outside from his room to find Dr. King’s body on the balcony floor, just 40 feet away.

“At first, it was just a matter of realizing the horror of the thing,” he recalled of Dr. King’s death by gunshot. “Then I knew I must record it for the world to see.”

Watch: Joseph Louw’s Eyewitness Testimony, Broadcast Three Days After Dr. King’s Assassination

In the moments immediately following Dr. King’s assassination, Joseph Louw was the only photographer on the scene. Dr. King’s friends gathered around his body and pointed in the direction of the shooter. Police with rifles swarmed around the motel. “As I looked at Dr. King,” he said, “I could almost feel the wound myself.”

Two nights prior, Louw and Dr. King had shared a moment on the balcony of the Lorraine Motel, looking up at a powerful storm brewing over Memphis. “For me,” Louw said, “that was the first time I had seen Martin Luther King as a man, as well as a great man.”

Following the assassination, Louw immediately returned to New York to develop his four rolls of film at the LIFE Magazine labs. His photos taken at the motel in Memphis would become one of the most recognizable images of the twentieth century.

PBL/NET and Louw agreed that any money received from the use of Louw’s photographs from the night Dr. King was assassinated would be contributed to organizations dedicated to the principles for which the late civil rights leader worked so assiduously.

Joseph Louw told LIFE Magazine that the last stage of developing the film was the “longest 10 minutes of my life. The first picture I looked at was Dr. King laying behind the railing. I never did photograph him full in the face. I felt I had to keep my distance and respect.”

Free At Last: Martin Luther King Documentary

Just three days after Dr. King’s death, THIRTEEN aired the unfinished PBL documentaryFree at Last (now streaming on THIRTEEN Specials, including Louw’s own eyewitness testimony.

Some of the photographs of that Joseph Louw (1945 – 2004) took on April 4, 1968 can be seen on the site of the International Center of Photography.