Troubling questions still remain about the 1994 assassination of the PRI's presidential candidate, Luis Donaldo Colosio.

Senior Mexican officials say they have never found hard evidence to support rumors that drug gangs were involved in the assassination last year of the governing party's presidential candidate, Luis Donaldo Colosio.

Ltd. "There hasn't been an assassination of the leading party's presidential candidate.

Citing new evidence of a conspiracy in the assassination of the governing party's presidential candidate last month, Mexican authorities today charged three men, including two former state police officials, with involvement in the killing.

That faith was tested in Mexico recently with the peasant uprising in Chiapas and the assassination of the ruling party's presidential candidate.

The action followed the assassination of Colombia's leading presidential candidate, who was an outspoken foe of the drug trade, and other Colombian officials.

Mr. Barco declared war on the drug traffickers in August after the assassination of the country's leading presidential candidate.

Three weeks after Mr. Castaneda was killed, the shock of his death was swept aside by the assassination here of the governing party's presidential candidate, Luis Donaldo Colosio.

Bitter party infighting led to the assassination of the PRI's candidate in 1994, and the party remains divided.

The drug war began in August after the assassination of the country's leading presidential candidate.