Questions Still Lack Answers in Colosio Probe : Mexico: New prosecutor will have to prove to a skeptical public that she is not part of a cover-up. Many doubt ‘lone assassin’ theory.

In a Spartan meeting room overlooking the colonial patio of the Mexican Senate building, a congressional committee charged with following the investigation into the murder of presidential candidate Luis Donaldo Colosio listened attentively. Dr. Rafael Moreno, the attorney general’s head of criminology, was outlining the questions that he said any crime investigation must answer:

“What happened? . . . Who is the murderer? Who is the victim? . . . When did it happen? . . . How? . . . Where? . . . What weapon was used? And finally, why?”

Two weeks later, early this month, Moreno and a dozen other forensics experts signed off on a report on Colosio’s murder that, for most Mexicans, left many of those questions without credible answers.

People simply do not believe their conclusion that accused killer Mario Aburto Martinez was the classic lone assassin, a deranged dissident determined to make his mark on history. In the national uproar that followed, President Carlos Salinas de Gortari ordered the investigation reopened.

Olga Islas, the new special prosecutor Salinas appointed, faces the daunting challenge of proving to a conspiracy-minded public that she is not participating in a cover-up by hard-line members of Colosio’s own ruling party, drug traffickers or someone else.

“I am not saying that there was a mastermind, just that the conclusions should be reached after a serious investigation,” said Juan Velazquez, an attorney representing Colosio’s widow, Diana Laura Riojas. “All I am doing is asking for an investigation.”

In doing so, Velazquez and Riojas are exercising her rights under Mexican law, which grants the victim’s family a standing equal to that of the defense or prosecution. The fragile-looking mother of two young children has become the voice for Mexicans demanding justice.

“They should talk with Mr. Aburto’s family; they should look into the references to third persons in his writing,” said Velazquez. “They should investigate.”

Aburto’s father, who lives in San Pedro, was subpoenaed to testify last week about his allegations that his son, a 23-year-old factory worker, met with three members of Colosio’s security team--who are now imprisoned as suspected plotters--and other security agents in the months before the slaying. “That certainly brings into question the theory that Mario acted alone,” said Peter Schey, attorney for the Aburto family.

The parents recently told The Times that their son had once applied to work as a state judicial police officer, and said he complained in the days before the assassination that he was being followed.

Besides talking with the family, it also appears likely that the new special prosecutor will attempt to retrace Aburto’s steps in Tijuana, where the murder occurred--a task that did not appear to have been done thoroughly during the first probe. There are accounts that Aburto grew increasingly moody and withdrawn in the final weeks, that he was dressing better and other signs that he was coming into money.

Other new leads are expected from the panel of five legal experts who are reviewing the original investigation’s 284 interviews, 29 technical studies, 80 videotapes and 1,621 photographs.

Some of the lingering questions the new prosecutor must answer are basic: The investigation has revealed that there was a far more extensive security force from an array of government and private agencies than anyone suspected. However, investigators have offered little explanation for how a presidential candidate could be shot in the head at point-blank range in the midst of nearly 70 security guards.

And she will be expected to sort through conflicting interpretations of existing evidence.

For example, repeated viewings of the videotapes recording the murder have produced starkly different versions of what happened. Like Aburto’s writings, the tapes were first submitted to a judge as evidence of a conspiracy that landed the three Colosio security agents in prison, accused of clearing a path in a crowd for the gunman. Later, the prosecutor dismissed the tapes as inconclusive and cited the writings as proof that Aburto acted alone.

Islas’ role is crucial, because investigators’ failure so far to answer the public’s questions has raised the specter of a dark force behind the killing that overshadows next month’s presidential election and casts suspicion on every decision made in the Byzantine world of Mexican politics. Officials at the highest levels of government are rumored to be disturbed by fears that the slaying may have been directed by a disenchanted faction of the ruling elite.

Much of the controversy surrounds Aburto himself: his treatment by the Mexican justice system, his writings and statements about mysterious political activities with influential people, and what some describe as changing and secretive behavior in the weeks before the slaying .

In confessions and news interviews, Aburto has declared that he only meant to wound the candidate and denied that the other accused suspects were involved--although witnesses say he hinted in his first confession that he had confederates.

Moreover, family and acquaintances say Aburto talked repeatedly about attending political meetings--reportedly boasting that he was paid to do so--and alluded to a mysterious political “project.” His address book contained the address and phone number of an elderly Tijuana leader of a faction of the ruling Institutional Revolutionary Party, known as PRI, and information about when the group met.

Investigators did not interview that political leader, Blas Manrique, until three months after the assassination--and have not explained the entry in the address book. When legislators asked former special prosecutor Miguel Montes Garcia last month whether he had spoken with all the people listed in Aburto’s address book, he told them the investigation was continuing.

Manrique told The Times in an interview that he never met Aburto, but suggested the young man may have been a government informer. “Maybe he was working for the police,” Manrique said.

That speculation is echoed by others, who suggest that the ambitious young laborer fits the classic profile of a domestic political spy used to infiltrate opposition groups, operatives known in Mexico as orejas , ears.

According to a scenario described by one Baja California government official, who asked not to be named, Aburto could have been recruited into an assassination plot after being cultivated as an informer.

Theorists further cite the allegations by family members that Aburto was friendly with an Interior Ministry agent, Jorge Antonio Sanchez Ortega, who was present at Colosio’s murder. He was investigated because his hands tested positive for having fired a gun and his shirt was stained with blood.

Although Sanchez Ortega was cleared, his actions at the fateful campaign rally may well be reviewed as part of the renewed inquiry.

Montes told the members of Congress that his questioning of Aburto had been limited because when he took over the case on March 28, the suspect had already been turned over to the court system. At that point, all questioning must be done in public hearings.

Meanwhile, Aburto’s family has complained that he is being held practically incommunicado.

Schey said he has been assured that under Mexican law, Aburto has the right to choose his own attorney. However, the family’s requests for him to see a lawyer, doctor or even them have been met with a wall of bureaucratic resistance.

The prosecutor referred them to the judge, who referred them to the prison authorities, who have not responded to calls or faxes, Schey said.

“They don’t want independent lawyers to visit him, they don’t want family members to talk with him, they don’t want doctors to examine him,” Schey concluded.