The Supreme Public Prosecutor's Office began a second round of questioning Sunday to determine if the supervisors of a suspicious Osaka prosecutor tried to cover up his alleged evidence-tampering, sources said.
The cross-examination will take about three days, the sources said.
The top prosecutors are expected to ask Hiromichi Otsubo and Motoaki Saga, the former chief and deputy chief of the special investigation department at the Osaka District Public Prosecutor's Office.
The two will be asked to explain their perceptions when they were told about the allegations against prosecutor Tsunehiko Maeda, 43, during a probe into a postal abuse case involving a senior health ministry official who was later acquitted.