Have you found any criminals in your family tree? If they were 'up before the beak' between 1805 and 1816, then the chances are that they are listed in the criminal registers below. I wonder what their fate was - were they transported or given the death sentence. The answer could be here.
One of the most difficult times to research is the 20th century as certain records are not yet available. There is a cracking little guide that can point you in the right direction. With Militia Muster Lists and Military History also available, your ancestors will not stay hidden for long.