I had taken a certificate program course in Forensics and one of the speakers that came in for the class worked with the local crime lab in computer forensics.
The guy told me that most of the stuff they deal with is child pornography. However there are other things, for example drug dealers that use computers for their records that are password protected (they have programs to figure out hte password), but they have all these neat toys and gadgets.
The person I spoke to told me that he started out as a state trooper and he just liked gadgets, and from what I understood the hiring occurred within the department so I don't think it was something that was advertised.