On 23 March 1994 the presidential candidate for Mexico's ruling Institutional Revolutionary Party, PRI, was shot dead in the border town of Tijuana. Luis Donaldo Colosio, who was expected to be the country's next leader, was killed when out campaigning. A sole gunman is still in jail for his murder, but Alfonso Durazo, Colosio's former private secretary, tells Mike Lanchin why he believes the murder was part of a wider political plot.Photo taken from Televisa TV broadcast showing amateur video footage of the moment that Luis Colosio was about to be shot dead during a campaign rally (credit: TELEVISA/AFP/Getty Images)