CSIs

What I don't get about all the csi shows is, are the crime scene investigators cops or scientists... Both perhaps!?
Are there real csi who do what television csi do!?
Somehow it doesn't seem right, especially when they question suspects.
They are not sworn peace officers, they are civilian employees of that certain law enforcement department. (I guess you can be a sworn civilian employee).
In real life, I'm not sure they have the authority to hold or question a suspect or even carry firearms.
I know it may not bother most people but it keeps me irritated!