Obstruction of Justice

The phrase Obstruction of Justice as technical meaning in a legal sense as a type of crime. The statutes of the various jurisdictions specify the phrase’s exact legal meaning in those venues. However, when used in the broader context of the English language, the phrase could describe acts that, while not illegal, are immoral or unjust. Simply put, it’s not unreasonable for someone to describe an act that prevents or delays a just outcome in a situation as “obstructing justice.”

With that in mind, how might one describe a prosecutor who prolonged an investigation long after he knew no crime had actually been committed?