A great documentary about this subject is "I am Evidence." It's by Mariska Hargitay of SVU (available on YouTube). They found huge backlogs in places like Chicago and LA County. When they started testing the Chicago kits they started to close a bunch of cases with arrests including finding several serial rapists. This is a matter of proper budgeting, making sure all kits get tested means a BUNCH more DNA specialized forensic scientists, but since more and more forensic evidence is DNA related, more scientists is a good thing.