The assassin stood unnoticed in the crowd. He listened as the man he was stalking pledged to help poor people, like the 3,000 gathered in a ramshackle neighborhood near Tijuana's airport. After a chorus of vivas, the candidate stepped down from the platform and, in his populist campaign style, waded into the crush to shake hands. The assassin edged up behind him, thrust a .38-cal. pistol at his head and fired. The bullet smashed through the candidate's skull, shattering his brain. Then the gunman leaned over and fired another bullet into the fallen man's stomach.
The first shot not only killed...