A recent decision by the special investigation squad of the Tokyo District Public Prosecutor's Office not to indict a local government employee for bribery, citing doubts over the credibility of his confession, has stunned police.

For many years, it was almost a foregone conclusion in law-enforcement circles that those arrested in bribery cases faced indictment.

The decision could represent a shift by prosecutors away from prioritizing confessions above all else in deciding whether to indict — a change observers say may be the result of high-profile cases involving top prosecutors in recent years in which courts have exonerated suspects.