SHIZUOKA (Kyodo) -- A lawyer for an 88-year-old man acquitted in a retrial over a 1966 quadruple murder case has sought about 217 million yen ($1.4 million) in state compensation for his nearly half-century wrongful detention, a source close to the matter said Wednesday.

The request for criminal compensation, entitled under Japanese law, was submitted to the Shizuoka District Court the same day after Iwao Hakamada's acquittal was finalized in October, marking the end of his family's decades-long fight to free him from death row.

Under Japan's Criminal Compensation Act, an acquitted person can receive up to 12,500 yen per day of detention. The court determines the compensation amount based on factors such as time spent in custody and potential future earnings.

As Hakamada's mental state deteriorated during his long incarceration, making communication difficult, his elder sister, Hideko Hakamada, 91, and a lawyer were appointed as his guardians. The lawyer filed the request.

The lawyer has also filed a request with the Shizuoka District Court to recover lawsuit fees.

"We want (the court) to take into consideration the fact that Mr. Hakamada has gone through unimaginable suffering and is still living in a delusional world due to prolonged detention," Hideyo Ogawa, a different lawyer who is part of Hakamada's defense team, said.

The former professional boxer spent about 47 years and seven months behind bars after he was arrested on Aug. 18, 1966. He was released on March 27, 2014, after new evidence raised doubts about his conviction, leading to the start of the retrial.

Hakamada was recognized as the world's longest-serving death row inmate.

Hakamada's defense team is also preparing a separate damages suit against the central government and the Shizuoka prefectural government over the false charge brought against him.

Hakamada, who was a live-in employee at a miso maker, was arrested in 1966 for allegedly killing the firm's senior managing director, his wife and two of their children, in Hamamatsu, Shizuoka Prefecture. His death sentence was finalized in 1980.

In granting Hakamada's acquittal in September last year, the Shizuoka District Court ruled that investigators had fabricated evidence, and prosecutors chose not to appeal.