Vladimiro Montesinos, the former spy chief who was once Peru's most feared man, went on trial today at a Lima prison guarded by hundreds of police commandos with automatic weapons.

"It is the beginning of the public trial of probably the most corrupt man in the history of Peru," said Ronald Gamarra, a special state attorney assigned to the Montesinos investigation.

Looking grayer than the last time he appeared in public, six months ago, the balding, bespectacled Montesinos, 57, walked into a prison courtroom for the opening of his first public trial.

He faces a charge of influence peddling, a minor offense among the dozens of counts before him that range from corruption to drug trafficking, arms dealing and directing a death squad.

He sat down stiff-backed beside his former mistress, Jacqueline Beltran, without greeting her. Montesinos is accused of using his reputed control of the judiciary during the previous decade to get Beltran's brother out of prison. He could be imprisoned for five years if convicted.

Montesinos, dressed in a blue silk shirt and dark slacks, showed little emotion as he faced a three-judge panel and listened to the charges against him. The former spy chief entered a written statement in which he exercised his right to remain silent and challenged the impartiality of the judges.

Montesinos is accused of building a criminal empire involving generals, legislators, the mass media and judges while he served as the most trusted aide to then-President Alberto Fujimori. Investigators say he bilked Peru of hundreds of millions of dollars during Fujimori's decade-long authoritarian rule.

Montesinos was brought by helicopter from a high-security naval prison to Lurigancho prison in a shantytown on the far side of Lima. He was in handcuffs and wore a bulletproof vest. Hundreds of police ringed the prison and sharpshooters perched on nearby houses and surrounding hills.

Montesinos has gone on a hunger strike and refused to testify as a witness in other cases. By questioning the impartiality of judges, he has forced a delay in his trials. Montesinos recently complained to prison psychologists that he was having thoughts of suicide.

Many in Peru contend Montesinos still wields influence over a judicial system he reputedly controlled with intimidation and bribes until Fujimori's regime collapsed in 2000. His corruption trial is viewed as a test of the independence of the courts.

In the cases that involve more serious charges, including murder and drug trafficking, the strength of the evidence is unclear. A judge ruled in December that there was insufficient evidence to try Montesinos on one count of drug trafficking.

Vladimiro Montesinos, a power in Peru during the 1990s, goes on trial in Lima for influence peddling.