Who does what in the U.S. legal system

There is no shortage of crime shows on TV. Solving mysterious, perverse and/or obscene murders seems to be a very popular spectator sport. I also watch my share of these shows. Some of the ones I watch include CSI, Jordan, Law & Order, Shark and Numb3rs. But while I enjoy these shows they also greatly confuse me.

Solving cases typically involves evaluating evidences, interrogating suspects and witnesses, checking alibis and trying to fit all of it together. The peculiar thing with the crime shows is that all of these things are done by a single profession in each show, but the profession changes between shows. It ranges from the coroner, crime scene investigators to cops or lawyers, all depending the particular show.

The only show (or rather set of shows) that seems to have a more realistic tack is Law & Order. They have all the professions of the legal system represented and working together. It's actually kind of cool to see how the cases starts out with the detectives to eventually move over to the attorneys who needs to make the final conviction happen.

Sure, I realize that this discrepancy between between series is there to cut down on the number of main characters and make their work seems central and important. But when you compare CSI and Shark it just seems ridiculous. Obviously, they can't both reflect the reality. And even if the truth is somewhere in the middle the gap between them is so big that I think they're both pretty far from how it's really done.

Oh well. I'm glad I got that off my chest.