Photographing Jack Ruby shooting Lee Harvey Oswald
On 24 November 1963 - two days after US President John F Kennedy was killed - the man arrested on suspicion of carrying out the assassination was himself shot dead.
The image of Jack Ruby firing a pistol at Lee Harvey Oswald is one of the most famous of the 20th Century. It was taken by Dallas Times-Herald photographer Bob Jackson and won him the Pulitzer Prize.
Now living in Denver, Colorado, he spoke to the BBC about taking the shot of a lifetime - and explained why being a split-second slower than a competitor made all the difference.
Produced by Markus Zeffler, Charly Jaffe and Amir Payam
First Person is a series of video features published every Monday on the BBC News website which tell the stories of unique individuals from all walks of life in their own words.
25 Nov 2013