The Osaka District Court on March 30 found Mr. Hiromichi Otsubo, former head of the Osaka District Public Prosecutors Office's special investigation squad, and his former deputy Mr. Motoaki Saga guilty of covering up evidence tampering by a subordinate, Mr. Tsunehiko Maeda.

The case should not be trivialized as a crime committed by two individuals, but should be regarded as a symptom of problems with the nation's prosecution as a whole.

The evidence in question was a floppy disk seized in connection with an alleged abuse of a postal discount system for disabled people. Ms. Atsuko Muraki, a former official of the health and welfare ministry, was indicted but was eventually acquitted in September 2010. Mr. Maeda was found guilty of tampering in April 2011.