sign his death warrant, so the death sentence was never carried out. Even Isaji Tanaka, who on 13 October 1967 announced in front of the press that he had signed the death warrants of 23 prisoners in one go, did not sign Hirasawa's death warrant, stating that he doubted Hirasawa's guilt. The poison was regarded as the readily obtainable potassium cyanide in Hirasawa's trial. One of the reasons given to doubt Hirasawa's guilt is because the victims' symptoms were clearly different from potassium cyanide poisoning, which is rapid. Keio University's contemporary investigation claimed that the true poison may have been acetone cyanohydrin, a military poison deliberately designed to be slow-acting, which Hirasawa could not have obtained. Death in prison Hirasawa remained in prison as a condemned criminal for the next 32 years. He spent his time painting and writing his autobiography . In 1981, Makoto Endo became the leader of Hirasawa's lawyers. Beside this case, he took part in controversial trials such as that of Norio Nagayama. The defense claimed that statute of limitations for his death penalty ran out in 1985. The death penalty has a 30-year statute of limitations under the Criminal Code of Japan, and so Endo appealed for his release. However, the Japanese court refused this argument, pointing out that the statute only applies in the case if a death row inmate escapes from prison and evades capture for 30 years. Japanese courts judge that the punishment begins when the minister signs the death warrant, which had never been done. His health deteriorated in 1987. On April 30, 1987, Amnesty International petitioned the Japanese government to release him, but Hirasawa died of pneumonia in a prison hospital on May 10. Bids for a posthumous retrial Even after Hirasawa's death, his son by adoption, Takehiko Hirasawa, tried to clear his name. Takehiko was the son of one of Sadamichi's supporters; he became the painter's adopted son while in university to take up the task of getting a retrial for Sadamichi, as his relatives were reluctant to pursue the case due to social prejudice. Takehiko also worked to recover several of Sadamichi's lost paintings and held exhibitions of his work. He and his lawyers submitted a 19th plea for retrial; Sadamichi's brain damage was also proved. , his lawyers had submitted new evidence to attempt to prove Hirasawa's innocence. In September 2013, Takehiko Hirasawa died alone at his