County to investigate possible wrongful convictions

http://tucson.com/news/county-to-investigate-possible-wrongful-convictions/article_e7ea5576-2106-5446-ba1b-ed515afb6c5e.html

Proof beyond a reasonable doubt is supposed to assure that only the guilty are convicted.  One has to wonder how it is that so many innocent individuals have been found by a jury to be guilty "beyond a reasonable doubt" when they were, in fact, innocent?  Perhaps if prosecutors were to more closely evaluate their cases, there would not be such a pressing need for prosecutors to go back and look for wrongful convictions...