Yet you have them...
http://hcnh.org/Departments/Sheriffs-Office-MainFirst aspect - elected position, city cops are not elected
Second aspect - Sheriffs can go into cities. Police have no authority outside of their city in most circumstances.
A very brief overview for Texas...What's the Difference Between Sheriff, Police and Constable?
Sheriffs serve warrants and a Federal Warrant being served in their county places them at the tip of the spear as to whether the search should even take place...if they're doing their job right.
They would damn sure know what was up if Form 4473s were listed in the warrant.
Your local Sheriff should be the contact point of ANY Federal law enforcement proceedings.
They could tell the Feds the matter is a State issue and that they had no jurisdiction.
That's what I get out of it, but I haven't gone in depth on the matter.
Rather crude, but it gives the jist.
Think of this...if your business/home were outside of city limits and Fed law enforcement had a warrant to serve, who would they report their actions too? Would they just go in and take action anyway?
Not city cops 'cause that's out of their jurisdiction. State cops? They would send it to the top county law enforcement division...the Sheriff.
Remember, they contacted the city police, not the Sheriff.
Who is the police Chief (an appointed position usually) and do they have political ties?
A US Marshall rides into town, tells the Sheriff about the warrant and they both go serve the warrant.