odysseus2000 wrote: its all very confusing to me as to when the FBI can get involved and on top of that is the various levels of State police, State Troupers and where they can and can't act. Meanwhile the University where I worked had its own security, as did Nasa as did the [expletive deleted] where the NASA site was.
All I know is that cities have cops, counties have sheriffs (who also police the courts and jails) and States have troopers. Highway patrol are State troopers who have jurisdiction on the major roads. Rangers are Federal and have jurisdiction in the national parks.
Then there are anomalies. Washington DC has cops but not an investigative force, so crimes in DC are investigated by the FBI even though the crime may be local. (I know this because a friend of mine was a victim of a fairly serious crime there).
The Presidio is wholly within the city of San Francisco but the police there are NP rangers - the city cops don't have jurisdiction although they can be invited to help.
I've never been sure what Federal marshalls do, but I think they are equivalent to sheriffs, except with a national remit.
Then there is the FBI, the DEA, the TSA, the coastguard, the military police, homeland security and border protection. The IRS is part of the Treasury but they have their own enforcement people as well.
