Ms. Atsuko Muraki, a former health and welfare ministry official, was acquitted in September 2010 of a charge of forging an official document concerning postage discounts for an organization for the disabled. Mr. Tsunehiko Maeda, a prosecutor of the Osaka District Public Prosecutors Office's special investigation squad in charge of her trial, was found to have tampered with a floppy disk allegedly containing the same text as the forged document. He was eventually given 18 months' imprisonment in April 2011.

On Sept. 12, the trial of his two former bosses — Mr. Hiromichi Otsubo and Mr. Motoaki Saga, respectively, the former head and vice head of the squad — started at the Osaka District Court. The two are accused of trying to hide the fact of floppy disk tampering despite being aware of Mr. Maeda's intentions. The Supreme Public Prosecutors Office indicted Mr. Otsubo and Mr. Saga.

The prosecution alleges that the two ordered Mr. Maeda to write a report that he had changed the floppy disk data by mistake even though they knew he had changed it intentionally, because of fear that findings of deliberate evidence tampering would negatively affect the squad's position in Ms. Muraki's trial. It also alleges that the two issued a gag order to other public prosecutors.