Assassination to Test Mexico Justice System : Investigation: Luis Donaldo Colosio’s killing and suspect’s interrogation raise suspicions of conspiracy.

The investigation into the assassination of ruling party presidential candidate Luis Donaldo Colosio has hooked the government’s credibility to one of Mexico’s most mistrusted institutions: the country’s criminal justice system.

The strain was already becoming evident the weekend after the shooting.

On Saturday, the attorney general’s office was forced to deny rumors that the suspect being held in a prison outside Mexico City is not the same person arrested in Tijuana, where Colosio was killed.

Atty. Gen. Diego Valades’ statement that Mario Aburto Martinez had confessed to the crime has also become suspect. The human rights activist who government officials said witnessed their interrogation of the prisoner has told reporters that he did not hear the confession.

Further, prominent opposition politician Porfirio Munoz Ledo has raised suspicions of a conspiracy, setting the stage for accusations of a cover-up, if the investigation shows that Aburto acted alone.

That is an inauspicious beginning for an investigation crucial to restoring the confidence of a citizenry shocked and angered by the violent death of a man most had expected to be their next president.

Colosio’s election was virtually assured because he was the candidate of the Institutional Revolutionary Party, or PRI, which has ruled Mexico for 65 years.

The mission would be difficult for law enforcement agencies in any country, but it is particularly tough in Mexico, where only 12% of the population respects the police--the same percentage that respects politicians. Both figures are from a recent survey in the demographic magazine Este Pais.

The situation is complicated by Mexicans’ long collective memory and a history of political murders and suspicious deaths.

Law enforcement officials have said the last thing they want is another controversy like the John F. Kennedy assassination: a political murder whose motive is still a mystery and whose investigation is questioned three decades later.

They have taken elaborate precautions to make sure that Aburto neither escapes nor gets killed himself, as did JFK assassin suspect Lee Harvey Oswald. The suspect’s transfer from Tijuana to a maximum-security prison outside Mexico City was kept quiet until Aburto was safely locked inside the country’s newest penitentiary Friday.

Guards with submachine guns surrounded Aburto, who was placed in a bulletproof glass cell for five-minute photo sessions with small groups of photographers Friday morning. Despite such precautions, an entirely different set of problems emerged when photographs of the prisoner appeared in Saturday newspapers.

The cleanshaven man in the photos looked so different from the bloodied, mustachioed figure shown on television Wednesday being led away by police from the murder scene that people suspected a switch.

“It is exactly the same person,” Valades said in a written statement. The only difference was that Aburto’s hair was combed and he was shaved, with his permission, the attorney general said.

Aburto’s identity was proven with fingerprints, he added. But the public remains skeptical.

To avoid charges--familiar in Mexico--that Aburto’s statement to police was obtained by torture, Jose Luis Perez Canchola, the Baja California state ombudsman for human rights, was asked to attend the interrogation.

After Valades said Aburto had confessed, however, Perez told reporters that he had heard no such statement. In addition, the human rights activist said he believes that the assassin did not act alone.

The possibility of a conspiracy was also voiced by Munoz Ledo, chairman of the opposition Democratic Revolutionary Party and formerly a PRI member. Munoz Ledo said police reports he had seen called Aburto a professional killer who was paid to execute Colosio.

A majority of Mexicans believe that there was a conspiracy to kill the candidate, opinion polls show.

Given Mexico’s history of political killings and the police record in solving them, those suspicions are understandable.

“No one has his life already paid for” is a common refrain among Mexican politicians, according to political historian Oscar Hinojosa.

Plutarco Elias Calles, the founder of the ruling party, was known for a series of executions in the 1930s. Politically ambitious generals also were killed, although less routinely, in the 1940s and 1950s.

Many Mexicans are suspicious about the 1969 airplane crash in which Carlos Alberto Madrazo died. Four years earlier, he had resigned as the PRI chairman, convinced that the party could not be reformed, and at the time of the crash rumors were circulating that he was planning to start a new party.

Add to that the 1988 car crash that killed Manuel Clouthier, a charismatic opposition party presidential candidate, and the murder of two key aides from another party, which is still under investigation.