NOPE! There does not have to be a crime for someone to Obstruct an official investigation.... an investigation is to find out if there are crimes or not... they may not have their answers as to whether a crime has been committed, at the time that a person tries to obstruct the official investigation, Obstruction of an investigation can keep the investigators from finding out the crimes committed.... or sending them on wild goose chases.
Just the ATTEMPT to do so, breaks our laws on obstruction.... as it should.
No crime is needed for someone to Obstruct justice. THAT is NOT in the law and not part of the laws on obstruction of an official investigation (no crimes when Scooter Libby AND Martha Stewart committed their obstruction)