I'm not sure what agency law is. Agencies don't make laws they make regulations, and no, regulations are not the same as laws. Regulations can have the force of laws.
The FBI is a Federal law enforcement agency responsible for security and law enforcement in the United States.
It depends on the specific agency.
A federal law enforcement agency that is the principal investigative arm of the Department of Justice
U.S. Marshals... BALLIN'
They are referring to the same thing. The Federal Government makes the US Law.
Question needs to be more specific. There are several federal law enforcement agencies that could be involved depending on the crime and the agency.
The oldest federal agency in the U.S.A is the U.S. Marshals Office Provided by Jamason Wells W.T.I. Florida
federal government's assumption of some regulatory powers in a particular field, with the stipulation that a state law on the same subject as a federal law is valid if it does not conflict with the federal law in the same area
The Drug Enforcement Agency or (DEA)
The Federal Reserve System
Federal law can supersede state law when it legislates the same area. This happens when a person can't obey both the Federal and the state law at the same time. When this is the case, it is the Federal law that the person should obey. Condo bylaws can be superseded by state or federal laws in the same manner. Further, state law can directly mandate how bylaws are written.
Depending on what law you are referring to contact your local law enforcement agency and ask, or your local, county, state, or federal legislators and complain.