A Tokyo court on Friday sentenced a 74-year-old far-left activist, who had been on the run for decades, to 20 years in prison for killing a policeman, among other charges, during a riot in Tokyo in 1971.

The decision by the Tokyo District Court came after Masaaki Osaka denied all charges, while prosecutors had sought life imprisonment. He was arrested in 2017, marking an end to his 45 years on the run.

According to the ruling, Osaka killed the policeman during a protest with students and other activists on Nov. 14, 1971, in Tokyo's Shibuya Ward against the ratification of the Japan-U.S. treaty on the reversion of Okinawa.

He was also convicted of injuring three other police officers and setting fire to a police station.

The court said the fatal attack on the officer with steel pipes and Molotov cocktails was "cruel and vicious" and that Osaka could not "avoid harsh criticism" for his years on the run.

Osaka's defense team appealed the ruling the same day.

The trial, which began in October last year, took over a year to conclude due to the need to compare testimony given in court with confessions and witness statements taken at the time of the event to establish the consistency and reliability of the evidence.

During the trial, Osaka admitted to participating in the riot but denied involvement in the policeman's death. He refused to speak about any help he had received during his life as a fugitive.

The trial was held without lay judges due to courts and civilians previously having been targeted by far-left activists.