Sunday's death of a death row inmate who had petitioned for decades for a retrial over his conviction in a 1961 murder case underscored the need to revamp the country's retrial system, according to lawyer Yuichi Kaido.

"The case had a chance of a retrial in 2005, but it was thrown into confusion because prosecutors filed an objection," said Kaido, who heads a nonprofit organization for prisoner rights.

Kaido was referring to the Nagoya High Court's order for a retrial for Masaru Okunishi in 2005 after he had submitted new evidence, which was later retracted by a separate department of the high court following the filing of an objection by prosecutors.