I'd imagine the authorities are MUCH lazier than that. I recall an episode of "First 48" (a kind of reality TV show following homicide detectives) where the suspect was on the run and occasionally posting to Facebook. The homicide detectives never bothered contacting Facebook for tracking information and instead just waited a few months till police officers found the suspect (who went on to kill himself in the standoff).

Anyway, my point is that I think police detectives are less like the expert professionals of TV shows and films and more like any other government employees. The vast majority of them would be doing well if they read their official training manuals and nevermind more exotic research like this hitman guide.