For 50 years, he chronicled disasters on the Mexican streets, moonlighting with the Red Cross so that he often arrived with the ambulance. Most are black and white, and they are the more beautiful - one, of a man swimming out to a corpse, bystanders reflected in the water, is astonishing - although occasionally colour works in his favour, as when a woman in red tries to jump from a tall building, or bright blood flows from a covered car accident victim.