A 20-year-old former policeman was sentenced Friday to 22 years in prison for shooting his boss to death at a police box in Hikone, Shiga Prefecture, last April.

In handing down the ruling, presiding Judge Hiroki Ito of the Otsu District Court said the man exhibited symptoms of adjustment disorder, but that it "did not strongly affect his capacity for making judgments and controlling behavior."

The ex-policeman, whose name is being withheld because he was a minor at the time of the crime, admitted to fatally shooting Shiga Prefectural Police Sgt. Akira Imoto, 41, who was in charge of training him. His lawyer claimed the man was suffering from an adjustment disorder because he was under psychological stress from strict training.

The judge found the man fully competent, focusing on the fact that he knew where to aim the gun to kill Imoto and maintained vivid memories of the incident, while admitting he had lost confidence through Imoto's harsh training and eventually unleashed his pent-up anger.

During the trial, the lawyer requested leniency, saying the plaintiff was in a mental state with limited capability for judging right from wrong. Prosecutors had sought a 25-year prison term.

According to the indictment, the former policeman shot Imoto in the back and head at a police box in Hikone at around 7:45 p.m. on April 11 and fled by police car. He had a handgun and ammunition in his possession until he was taken into custody at 8:30 p.m. the same day.