JEFFERSON CITY, Mo. (AP) _ Mel Carnahan, who risked his political future as Missouri's governor by raising taxes for schools and once commuted a death sentence at the request of the pope, was killed in a small plane crash Monday night. He was 66.

Carnahan died along with his eldest son, Roger Carnahan, and a campaign aide, Chris Sifford. The cause of the crash near St. Louis was not immediately determined.

The two-term Democrat had hoped to parlay his pro-education reputation into a U.S. Senate seat. He was battling incumbent Sen. John Ashcroft, a Republican, for the seat once held by Harry S. Truman.

During nearly eight years in office, Carnahan mandated new academic standards and raised state taxes by $315 million in 1993 to shrink classes, boost teacher training and buy classroom computers.

The move, which came after a state judge threw out the state's education funding system and ignored a campaign promise for a statewide vote on the issue, paid off when Carnahan was re-elected by a landslide in 1996.

``I did what I thought was right,'' Carnahan said in a 1996 interview, a common theme for the Baptist deacon who wore straight-arrow lapel pins to symbolize high ethical standards.

``The people of Missouri should know that their children and their children's children will be better off because of Mel Carnahan's dedication to them,'' said Ed Quick, the state Senate president pro tem.

Melvin Eugene Carnahan was born Feb. 11, 1934, in Birch Tree, nestled in southern Missouri's Ozark Mountains.

His parents were both rural teachers. His father, A.S.J. Carnahan, went on to serve in the U.S. House for 14 years and was the first U.S. ambassador to Sierra Leone under President Kennedy.

Carnahan, a lawyer, spent two years in the Air Force after graduating from George Washington University in Washington, D.C. He failed the physical for becoming an Air Force pilot, but later earned his private pilot's license and sometimes slipped away to escape the pressures of work.

Carnahan won his first public election at age 26 as a municipal judge in his hometown of Rolla. He was elected to the Missouri House of Representatives two years later and served two terms, and later served as state treasurer.

In 1988, Carnahan was elected lieutenant governor and four years later won the governor's office in a landslide. He was tested early as a crisis manager when the Missouri and Mississippi rivers roared beyond their banks during record flooding in 1993.

The avuncular Carnahan displayed easy rapport with young people, once ``pardoning'' a boy who had been grounded by his parents for telling a fib. He also poked fun at his stuffy image, donning elaborate costumes at Halloween to welcome thousands of trick-or-treaters to the governor's mansion.

A strong death penalty proponent, Carnahan made headlines last year during Pope John Paul II's visit to St. Louis when he honored a personal request from the pope and spared a convicted murderer from the death chamber.

Also last year, he apologized for his youthful insensitivity for appearing in blackface makeup in a couple of hometown minstrel shows in the early 1960s after photos surfaced.

He oversaw a period of record state economic prosperity and was quick to note the creation of 300,000 jobs and development of Missouri's first strategic economic plan during his first term.

Hundreds of millions of dollars were spent on his watch for new prisons, and he signed a number of new crime-fighting laws. But seven years after the school tax legislation, Carnahan still considered it his proudest accomplishment.

On Sunday, after a debate with Ashcroft in Kansas City, Carnahan said: ``It felt good. I think I made my case for becoming Missouri's next U.S. senator and I hope the people will see fit to give me the job.''

Carnahan is survived by his wife, Jean, and three children, Russ, Robin and Tom.