Unanswered: Looking for a comedy movie

I watched this movie probably 10+ years ago on HBO which i do not remember the name. I would categorized it as comedy because i find it funny, have no idea what the actual category it belongs.
The protagonist committed a murder and was able to get away with it for some reason. And as the story proceeds, the protagonist met a sheriff/cop/detective and accidentally help the sheriff/cop/detective solved other cases while trying not to get caught for murder the protagonist committed.
(spoiler & some scene may not be accurate as that was a long time ago i watched the movie, sorry about that :( ) One of the case is that he helped catch a thief is as everyone thought the thief was gone but protagonist pointed out the thief was still in the perimeter while trying to hide the evidence protagonist had committed a crime.
And at the end of the movie, no one find out the protagonist had committed the murder and he was actually able to convinced the sheriff he was not the one the sheriff was after. However, the the sheriff still send the protagonist to prison for the exact same crime only because the sheriff had find out the protagonist had slept with sheriff's wife.
I found it so funny so i categorize it as comedy, would be grateful if some one knows what it is called.