The sister of former Colombian President Cesar Gaviria was killed late Thursday in a botched kidnapping that underscored fears of violence a month before national elections.

Liliana Gaviria, 52, a real estate agent, was killed by unknown assailants in the province of Risaralda, 110 miles west of Bogota.

Cesar Gaviria was president of Colombia between 1990-1994, before becoming secretary general of the Organization of American States. He currently leads the main opposition party, the Liberals.

``It pains us. It pains us greatly that such crimes occur,'' said President Alvaro Uribe, announcing a $430,000 reward for the capture of those responsible. ``The government will do all in its power to make sure this crime doesn't go unpunished.''

Between four and eight armed men intercepted Gaviria as she was traveling with her security detail. In the ensuing shootout, one of her bodyguards was killed and two of the kidnappers were injured, said Uberney Marin, mayor of the nearby city of Pereira.

Gaviria's body was found about 15 minutes after her abduction.

Colombian elections have traditionally been marked by violence as leftist rebels, far-right paramilitaries and drug-traffickers attempt to assert influence.

Despite a widening corruption scandal, Uribe continues to hold a commanding lead in polls ahead of the May 28 election. Voters appear to approve of his dogged pursuit of leftist rebels, which is credited with a dramatic drop in kidnapping and politically motivated homicides.

Cesar Gaviria's political career has been framed by the violence that has gripped Colombia for decades.

Ten years ago this month, his brother was kidnapped and kept for 70 days by a leftist rebel group before being set free in exchange for the release of eight prisoners.

In 1989, he was campaign manager for leading presidential candidate and anti-corruption crusader Luis Carlos Galan, who was assassinated at a rally by gunmen working for cocaine kingpin Pablo Escobar's Medellin cartel. Gaviria replaced Galan as the Liberal Party's candidate and went on to win the election.

Escobar was killed in 1993 during a rooftop shootout in Medellin, while Gaviria was in office.