I think it depends on how you do it. My grandpoppa killed himself by stepping in front of a train but didn't leave any clue he was going to do, beacuse it was on a railway line there was a coroner's inquest etc, this also might happen if you od or similar but maybe not with something like hanging.
Don't know how many apparent suicides get investigated as murders or accident, probably depends on a bunch of stuff.
Good luck brother