Katsumi Murase, a former senior official in the Nagoya Municipal Government, still remembers the time in 2003 when prosecutors interrogated him over a bid-rigging case in connection with a road cleaning contract.

Murase, 69, was arrested and indicted for allegedly leaking crucial information used in the alleged bid-rigging but was later acquitted — a verdict that was finalized.

"Your subordinate claims you should know about it," Murase recalled one of the prosecutors telling him during the interrogation. His colleagues apparently told prosecutors that Murase had given the green light to leak the winning bid price.