Diego Fernandez de Cevallos ran unsuccessfully for president in 1994. He had been missing since May, when his vehicle was found near his ranch in the central state of Queretaro. The kidnapping was the highest profile and most brazen in Mexico’s recent history.
Source: http://www.npr.org/2010/12/20/132220289/kidnappers-free-mexican-politician?ft=1&f=1004