Fifteen agents of Gen. Augusto Pinochet's regime were sentenced Friday to prison terms ranging from 5 to 18 years for the revenge killing of three dissidents after a bloody but unsuccessful 1986 attempt on the dictator's life.

The longest sentence, 18 years, was levied on Alvaro Corbalan, a former chief of operations for Pinochet's feared security service, the National Information Central.

Corbalan, a retired army major, and most of the others sentenced Friday were already serving sentences for other human rights violations during Pinochet's 1973-90 dictatorship.

One, retired police captain Ivan Quiroz, has been at large since fleeing after being sentenced in another human rights case this year.

According to the court, the 15 security agents picked journalist Jose Carrasco and the other two dissidents at their homes during the night of Sep. 7, 1986 and killed them in retaliation for the attempt hours earlier on Pinochet's life.

A pro-Communist guerrilla gang staged the attack on Pinochet's motorcade in the Andes foothills just outside Santiago. The former dictator survived, but five bodyguards were killed and 11 wounded.

A subsequent investigation determined that the three victims were chosen to be killed in retaliation because they were known to be members of leftist groups, even though they had no involvement in the attack against Pinochet.

Pinochet died last December of heart problems at age 91.