Jesús Palacio Díaz refereed two matches at the World Cup 1986 in Mexico. FIFA ref from 1983 until 1989.
In fact Diaz was designated to officiate at the 1990 World Cup as well, but he resigned. Diaz wrote a letter to FIFA stating: "My wife and children have begged me to give up refereeing. When it's a matter of life and death you have to consider the feelings of others. I can't keep on tormenting my family*".
A year before that a national referee, Alvaro Ortega, had been killed by the Medellin cartel and most referees had been threatened.
* from David Goldbaltt: The Ball is Round, Goldblatt cites J. King.