Mr. Hiroshi Obayashi, head of the Supreme Public Prosecutors Office, is to resign Monday over allegations that a member of the Osaka District Public Prosecutors Office's special investigation squad tampered with evidence and that the Osaka prosecutor's two bosses tried to shield the prosecutor from accusations.

The incident occurred in connection with the alleged fabrication of an official document by Ms. Atsuko Muraki, a former welfare ministry bureau chief, to help an organization receive a postage discount perk reserved for the disabled. Ms. Muraki was acquitted Sept. 10, and it has become evident that there was no evidence to support her indictment.

Mr. Obayashi, who was assigned to his current position in June, had nothing to do with the decision to indict Ms. Muraki. But he is to step down to take responsibility for the indictments of the elite investigation squad prosecutor and the two former bosses of that prosecutor.