Lawyers for Iwao Hakamata, who was acquitted in a retrial for a 1966 murder case in Shizuoka Prefecture, plan to sue the central and prefectural governments for damages in August.
They aim to take the legal action on Aug. 18, the date when Hakamata was arrested in 1966.
Last month, the Shizuoka District Court awarded Hakamata some ¥217 million ($1.44 million) under the criminal compensation law for his unjust detention of over 47 years.
Hideyo Ogawa, the head of Hakamata's defense team, told reporters that criminal compensation is "not enough" for the harm caused by the ex-boxer's unjust detention.
"We'll seek damages and clarify the cause of the false charge," he added.
Hakamata was arrested by the Shizuoka prefectural police on suspicion of robbery and murder of a family of four. Following his conviction, his death sentence was finalized in 1980 before he was granted a retrial in 2014 and ordered to be released by the district court. By then, he had already been detained for 47 years and seven months.
Hakamata was acquitted in September last year, and in the following month, the Shizuoka District Public Prosecutors Office waived its right to appeal, which finally led to the ex-boxer's exoneration.
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