I laugh at shows like NCIS....from what I heard the most they ever do is look into stolen stuff and the occasional assault.
They used to bug our phones, search our barracks rooms, and follow us around town. One time they were following me in a white blazer with heavy tinted windows. They were so blatant about it that even I noticed. So I drove around town for about an hour with them 3 car lengths behind me. I took them to the base lake and led them into a dead end. They finally stopped following me after I waved.
Other then that they spent a lot of time watching a few girls which were sleeping together.
When you think NCIS, think Clayton Lonetree, the USS Iowa, and thousands of gay ex-sailors.