Japanese traditional seasoning “miso” accelerates alteration of bloodstain color: Proof of innocent for a murder committed in 1966

In 1966, a miso company executive and his family were murdered, and their house was set on fire. A company employee was arrested two months after the crime. His name is Mr. Iwao Hakamada who was a professional boxer accomplishing innocent 58 years later. In 1967, the prosecution argued that bloodstained clothing found in a miso tank belonged to the accused. The court then accepted this evidence, sentencing him to death in 1968. The sentence was upheld by higher courts in 1976 and 1980. In 2014, after a plea from the defense, the district court ordered a retrial and released him despite his having been on death row, citing doubts about the bloodstain remaining reddish after being submerged in miso for over a year. However, in 2018, the high court overruled the lower court's verdict of opening a retrial. The Supreme Court reviewed the case and returned it to the high court for reconsideration 2 years later, emphasizing that the issue of blood discoloration had not yet been fully examined then. The defense team enlisted us to explain the bloodstain discoloration mechanism of clothing in miso. We conducted experiments investigating alteration of blood and bloodstain color by drying and/or under similar condition in miso. The color of blood and bloodstains was observed under low pH and/or high salt concentration conditions for four days to confirm that blood and blood stain could not remain reddish in miso for over a year. Results showed that the blood and bloodstain lost its redness and turned dark brown and/or blackish color in a few days after being in simulation of the environment found in miso. Furthermore, plain dried bloodstain would have turned brown in a few weeks due to oxidation from exposure to oxygen in the air. These results suggested that the five bloodstained articles of clothing, which were critical pieces of evidence for the guilty verdict, were prepared just before they were discovered, rather than having been hidden in miso tank after the murder. We submitted these scientific data to the high court demonstrating that the bloodstain of clothing hidden in miso for over a year could not have remained reddish, and were summoned as experts in 2023 at a high court and 2024 at a district court for a deposition. The court rendered a final verdict of not guilty, terminating his 56 years on death row. This case was a rare case in which forensic findings proved a wrongful conviction that had occurred 58 years earlier. While this study provides novel insight into miso- and the other salty or fermented food-related forensic contexts, limitations include a controlled lab setting and a focus on pH and salt concentration. These results highlight the need for forensic practitioners to consider food-derived environments during blood evidence evaluation.