Public prosecutors plan to file a special appeal against the most recent high court decision for a retrial of an 87-year-old man convicted in a high-profile 1966 multiple murder case, informed sources said Thursday.

On Monday, the Tokyo High Court decided to reopen the case after the Supreme Court in December 2020 canceled the high court's previous ruling rejecting the retrial plea by Iwao Hakamata and send the case back. The decision was regarded as an acquittal ruling.

If the Tokyo High Public Prosecutor's Office actually brings the appeal to the Supreme Court by the deadline on next Monday, the top court will have to examine again whether Hakamata should be retried or not, although nearly 15 years have passed since he filed the second retrial petition in 2008.

The death sentence for him over the murder case in Shizuoka Prefecture was finalized in 1980. In the case, four members of the family of an executive of a miso company were killed. Hakamata was a worker of the company.

In 2014, Shizuoka District Court granted a retrial, and Hakamata was released. But the ruling was overturned by Tokyo High Court in 2018.

In its latest ruling, the high court pointed to the possibility of the most crucial evidence having been effectively fabricated by investigative authorities.

Later, the high public prosecutor's office said in a comment that the ruling was regrettable.