America’s greatest civil rights leader and most famous advocate of non-violence was shot standing on the balcony of the Lorraine Motel at the age of 39. King traveled to Memphis to support a march for black sanitation workers on strike for better pay and wages. While Dr. King stood outside room number 306 at the motel, a rifle bullet was fired from a nearby rooming house. He was pronounced dead an hour later, making him the fourth assassination of a high-profile person in the U.S. in less than five years, after John F. Kennedy, Medgar Evers, and Malcolm X.

Joseph Louw, a South African photographer and filmmaker at work on a documentary about King, stayed three doors down from King. When he heard the shot fired and realized he couldn’t help, he got his camera out. Louw captured the chaos and emotion that followed, making an image engrained in our memories. As King lay unconscious on the balcony, his peers are pointing at the assassin, who was getting away.

Who was the assassin? Half a century later, there are still questions about why exactly the civil rights leader was assassinated and whether the shooter acted alone. However, federal authorities are confident that James Earl Ray, a career criminal who had escaped Missouri State Penitentiary one year prior, shot MLK. He was spotted at the scene and his fingerprints were identified on the gun. He pleaded guilty, and then received a 99-year prison sentence. But others believed there was more to the story. Conspiracy theories began to circulate right away that even if Ray fired the gun, he did so because of larger forces.

Check out the gallery above to see what the scene at MLK’s assassination looked like. Warning: A few of the images are graphic.