The Supreme Court on Thursday turned down a petition for a retrial by a man on death row for the 1961 murders of five women who drank poisoned wine in Nabari, Mie Prefecture.
In making the plea for Masaru Okunishi, 87, — his seventh — the defense team presented the opinion of an expert who found the poison used in the crime was not tetraethyl pyrophosphate, as determined in the final ruling.
However, the top court's First Petty Bench unanimously rejected it, saying Okunishi could have used the pesticide, as he initially confessed to doing.
In response, the defense team said it plans to file another plea for a retrial with the Nagoya High Court in the near future.
On March 28, 1961, 17 people were poisoned at a community meeting in Nabari. Five of them, including Okunishi's wife, died.
The Tsu District Court acquitted Okunishi in 1964 for lack of evidence, but the Nagoya High Court sentenced him to death in 1969, finalized by the Supreme Court in 1972.
Accepting his petition for retrial, the high court decided in 2005 to reopen the case and suspend the execution, but another panel of the high court nullified the decision the next year, accepting the appeal of prosecutors.
His petition was again rejected by the high court last year after having the case sent back by the top court, leading Okunishi to file a special appeal to the Supreme Court.
In deteriorating health, Okunishi is in serious condition at a medical prison in the western Tokyo suburb of Hachioji, where he has been held since May.