PORTLAND — Maine’s supreme court has rejected a Turner man’s appeal claiming his 40-year sentence for killing his wife was excessive.

Justices on Tuesday affirmed the sentence of 48-year-old Brian Nichols, who pleaded guilty to murder for fatally shooting Jane Tetreault in their Turner home in May 2010. Nichols told police he shot his wife in the head because he erroneously suspected her of cheating.

Nichols’ attorney appealed the 40-year sentence, claiming it was excessive compared to comparable cases.

In a unanimous decision, supreme court justices not only rejected Nichols’ claim, but also commended the lower-court judge for conducting an exemplary sentencing hearing and for demonstrating thoughtful consideration before imposing the sentence.