Juan Briones Davila, former Peruvian Interior Minister, helped disgraced President Alberto Fujimori send tanks to shut down Congress and Peru's judiciary in 1992. Davila has been sentenced to 10 years in prison.
Nine other ministers who served Fujimori were given four-year suspended sentences in the decision by a panel of Supreme Court justices announced late Monday.
Davila got the stiffest sentence because the judges ruled he played a major role in planning and carrying out the so-called "self-coup" by Fujimori, who went on to rewrite the nation's constitution and oversee the election of a legislature stacked with his supporters.
Under his 1993 constitution, Fujimori went on to win re-election in 1995 and 2000 in voting widely condemned by international observers as being fixed in his favor.
Fujimori, 69, fled to Japan seven years ago as his government collapsed in a corruption scandal, only to turn up in Chile in 2005. He was extradited to Peru in September.
His trial on charges of ordering death squad killings and kidnappings is scheduled to begin in December.
The former president faces up to 30 years in prison if convicted in the 1992 slayings of nine students and a professor at La Cantuta University, and the 1991 killings of 15 people in Lima's Barrios Altos neighborhood.
Fujimori calls the charges against him politically motivated. He faces a total of seven human rights and corruption charges.