LAWTON (AP) -- A former Duncan firefighter who shot and killed an Oklahoma Highway Patrol trooper was formally sentenced to death Thursday by a Comanche County judge.

District Judge Mark Smith handed down the death sentence to Ricky Ray Malone, who was convicted of first-degree murder in the Dec. 26, 2003, death of trooper Nikky Joe Green. Green was shot twice in the back of the head after a struggle on a Cotton County road.

A Comanche County jury recommended a death sentence after finding Malone guilty last month.

Malone, 30, testified he was operating a mobile methamphetamine lab in a car. Green approached the vehicle and lost his gun in a struggle after slapping a handcuff on one of Malone's wrists. Green was shot with his own weapon. Portions of the crime were captured on Green's dashboard-mounted video camera.

Malone said he was in drug-induced haze at the time of the killing and thought he was fighting for his life against a robber. He claimed voices in his head told him to shoot Green, 35.

Green's widow spoke with District Attorney Robert Schulte before she left the courtroom with family and friends. Oklahoma Highway Patrol Chief Col. Gary Adams, who attended the sentencing along with OHP troopers from across the state, thanked jurors.

"I know it was not an easy decision," he said, adding that the Highway Patrol believes justice has been done.

"We were very satisfied with the outcome," he said.

Malone glanced at his wife, Colleen, and his family before he was led away.

One of his attorneys, Don Gutteridge, said Malone handle his sentence well.

"He's a pretty laid-back guy," Gutteridge said.

During the penalty phase of the trial, Schulte had asked jurors to return a death penalty.

"What kind of a person can put a high velocity weapon to a man's head while he's praying and pull the trigger?" Schulte said. "A lot people can't put a stray dog down that way -- this man put a human being down that way.

"Anything less than the death penalty would be a travesty."

At least 30 other Oklahoma Highway Patrol troopers have died in the line of duty since 1941.

Before Green, the last trooper to die in the line of duty was Chris Van Krevelen who was killed on Thanksgiving Day 2002 in an automobile accident while responding to a report of a train-car accident in Enid.