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.

On April 9, the Metropolitan Police Department arrested an employee of Kita Ward in central Tokyo, alleging the civil servant had received ¥5 million in cash in return for giving a construction company a tip on the bid price of a project to build a public school building.

The Tokyo police also arrested a senior managing director of the construction company on suspicion of bribing the official. But the prosecutors eventually decided against filing an indictment in June.

In the period leading up to the arrests, police interviewed the government employee on several occasions, starting in December. Interviews began in the evening after the employee finished work and sometimes extended late into the night, with investigators sometimes kicking the desk, the civil servant’s lawyer said.

The employee also faced apparently threatening remarks by the police such as “Are you not taking the police seriously?” and “Do you want us to bring your wife here to hear the story?” the lawyer said. “(My client) admitted the charge reluctantly, out of fear.”

In investigations into bribery, police and prosecutors collaborate with each other in gathering evidence and building a case. If they encounter a problem, they may drop the investigation. Otherwise, an “unwritten rule” used to be that those who were arrested would be indicted.

In the case in question, however, on April 30, the special investigation squad of the Tokyo prosecutor’s office, which had supported the two suspects’ arrests by the police, released them.

One of the police investigators said the decision had come “out of the blue.” Police working the case were stunned.

According to a source close to the prosecutors, the special investigation unit went through the investigation materials again after the employee retracted his confession, and found evidence inconsistent with his earlier statement owning up to the bribery.

The prosecutors continued the investigation even after the employee’s release, but determined there was insufficient evidence to win a conviction. The decision against an indictment was made June 24, the source said.

Police officials remain incensed. “Because prosecutors told the (construction firm) official that the employee had now started to deny the allegations, the official also reversed his position and denied them himself,” a police source said.

“It’s just unbelievable in a bribery case that they divulged what the bribe taker said” to the bribe giver, the source said.

A senior prosecutor said, “I cannot say this loudly, but we used to indict suspects if their confessions were roughly consistent.”

“But now, the evidence-gathering capabilities of the defense have increased significantly. It is difficult (to indict suspects) when we have even the slightest element of contradiction,” the prosecutor said.

The approach of special investigation units to build cases based on confessions was thrown into question after an elite prosecutor of the Osaka District Public Prosecutor’s Office was found guilty of tampering with evidence in a 2010 case in which health ministry official Atsuko Muraki allegedly forged a document to enable an unqualified organization to take advantage of a postal discount service. She was exonerated.