I have done some research about the “Homeland Security Police” and here are my results.
The name they are go by is Federal Protective Service Police.
They are funded by the 9-11 fees that were added to all airline tickets & other transportation tickets.
They are primary assigned to federal buildings throughout the country.
In cities around the country they have the cars that look and drive like normal cop cars.
They have the white “U.S. Government” license plates.
It is unknown at this time why they are allowed to petrol the streets.
The photo below is from the downtown U.S. Post Office in Fort Collins.
It is a better one then the one I took before.
A story was done about them and it is also at the link below