Prosecutors must swiftly accept Thursday’s Shizuoka District Court decision to reopen a high-profile 1966 murder case and get to the truth behind the conviction of former professional boxer Iwao Hakamada, the Japan branch of Amnesty International said after the ruling.

After nearly five decades in which Hakamada, now 78, has been in solitary confinement, no further attempts to delay the retrial are tolerable, the group said in a written statement, adding that his physical and mental health are in decline.

The group described Hakamada’s death sentence, which was finalized by the Supreme Court in 1980, as fraught with allegations that he was coerced and tortured into confessing. It also noted that it wasn’t until after 2008 that prosecutors disclosed more than 600 pieces of new evidence, some of which undermined the veracity of their earlier evidence. Amnesty said the case represents an attempt to “cover up the truth” and blasted it as an act of “extreme injustice.”

The government, it said, should learn from the “tragedy” and prevent a recurrence, especially by overhauling the judicial system, including mandating full recordings of interrogations and abolishing “daiyo kangoku,” the substitute detention cells in police stations, it said.

Capital punishment is an “extremely brutal” affront to human dignity and utterly unforgivable, the group said.

“We strongly urge the Japanese government to put a moratorium on executions of all death row inmates, including Hakamada, and kick off a nationwide debate on the system,” it said.

Akira Kitani, a judge-turned-lawyer who considers it his lifetime mission to eradicate wrongful convictions, said at an event hosted by Amnesty on Thursday that 48 years in solitary confinement is “egregious.” The prosecutors’ long-standing reluctance to disclose information, he said, is mostly responsible for what happened to Hakamada.

He also described the case as a keen reminder that Japanese judges tend to be “blindly reliant” on authorities’ claims and must be more critical of what they say.

Regarding capital punishment, he said it’s a “barbaric and brutal” custom that needs to be stamped out.

Despite the popular belief that Japanese criminal trials are conducted very carefully, “it’s always possible for a miscarriage of justice to happen.”

The conviction rate in Japan is about 99 percent.