The state’s highest court upheld a lower court ruling Tuesday letting stand the sentence of a Turner man convicted of murder in his wife’s 2010 slaying.

An attorney for Brian Nichols, 48, argued before the Maine Supreme Judicial Court in May that the trial court erred when it failed to properly compare the basic sentence in this case to basic periods of incarceration for defendants in comparable cases. Adam Sherman, Nichols’ attorney, also argued that Active Retired Justice Robert Clifford failed to accurately place on a continuum of seriousness the manner in which the crime occurred compared with other ways it could be committed.

Sherman complained to the seven-member court in Portland that no central, accurate database is accessible to defense attorneys in Maine that provides basic sentences set by the courts in murder cases. He said he struggled to find more than two such sentences after an exhaustive search, but filed with the court many final sentences.

By contrast, prosecutors presented four basic sentences in similar murder cases for the court to consider during sentencing.

In a unanimous decision, the high court decided that Clifford didn’t misapply sentencing principles in imposing Nichols’ basic sentence. And the basic term set by the court was not an abuse of its power, Justice Andrew Mead wrote for the court.

Nichols fatally shot his wife, Jane Tetreault, 38, in bed at their house because he suspected her of having an affair, an accusation police later said was unfounded.

His trial attorney had said his client’s mental state was a mix of clinical problems, including paranoia, mania, delusions, personality disorder, anxiety and possibly schizophrenia.

Nichols was sentenced a year ago by Clifford after Nichols’ guilty plea a month earlier to intentional and knowing murder, which carries a sentence of 25 years to life in prison.

Nichols and prosecutors had agreed to a 42-year cap. Nichols had then argued for a sentence of 35 years, starting at a basic sentence of 30 to 35 years. Prosecutors urged the maximum.

Clifford settled on a 40-year sentence, after considering other murders committed in similar circumstances and after weighing factors that might add or subtract time from a basic sentence of 35 to 40 years.

The basic sentence is the first step of a statutory three-step sentencing process in Maine. A basic sentence is reached in the first step, after considering the nature and seriousness of the crime as committed by the defendant.

In Nichols’ case, the court considered that Nichols used a firearm, shot his wife at close range in or near her mouth, was premeditated in his actions, was in a jealous rage and committed the act in close proximity to their son.