My story will take place in a world that resembles ours but is not. The continent-wide nation where it happens will have a political and judicial system similar to that of the US.
I would need more info about how a federal police would work in that kind of state. To get a good idea of what the agents can do in their jurisdiction, think 80% FBI-20% CIA or something like that (unless FBI agents are allowed to do undercover ops ? I am so ignorant).
What are the procedures to interogate witnesses ? After an unxplained death, the staff of a club will have to answer a few questions. They will be asked to come to the police Headquarters and sit in one of those bland interrogation room with a false mirror.
If I remember well, it is not necessary for the police to notify the witness of his/her rights if they are not considered suspects, and what they say will not be held against them should the case go to the tribunal.
The police think something is fishy with the club, but they don't want to alert anyone in there. they have a legitimate reason to call the staff in as witness because a body was found just putside the club by a staff member and he was a regular. How would they notify each member of staff that they need to go to Headquarters to testify and such ?
So, to be very not precise, what would happen ?
[EDIT : thanks guys, my question is mostly answered, but if anyone thinks something grievously imortant hasn't been mentioned, feel free to drop another line.]