Roswell Gilbert, 75, was convicted yesterday of killing his 73-year-old, incurably ill wife in what he called an act of love and the prosecutor called a cold and calculated murder.

Circuit Court Judge Thomas Coker Jr. sentenced Gilbert to 25 years in prison with no chance of parole, as required by Florida law.

"I don't feel like I committed a crime at all," Gilbert said. "Justice is on my side but the law is on somebody else's." His lawyer said he would appeal.

Gilbert said he fired two bullets into his wife's brain last March because incurable osteoporosis and Alzheimer's disease had racked her with pain. The couple had been married 51 years.

Assistant State Attorney Kelly Hancock argued that Emily Gilbert's condition was not as bad as the defense contended, saying she could walk unassisted and went to lunch with her husband 90 minutes before he killed her.

Hancock said Gilbert had decided that his wife "was a psycho -- that's the word he used, 'psycho.' Don't let sympathy get in the way of the cold, hard facts."

But in his final statement, defense attorney Joseph Varon called the killing "the greatest act of love and of mercy."

A friend of the Gilberts testified during the trial that minutes before the shooting she heard Emily Gilbert pleading with her husband to "let me die."