Trying to make sure Justice is truly served, by making sure an investigation isn’t going toward what would be a false conclusion, cannot be defined as ‘obstruction’.
There’s a great article on Obstruction of Justice at the American Thinker.
Here’s a great take for all to consider: “Regardless of how an obstruction law might read, no citizen who is innocent of a crime should ever be found guilty of having obstructed justice if his actions facilitated a correct conclusion regarding it.”
(emphasis added)