What are the top companies hiring veterans trained in law enforcement?

Any of the security firms providing contracted services. If you want to know who's doing what what and where on the Federal side, check out fedbizopps.gov. You'll see a list of the usual suspects...

Google will tell you the big guys, but "top" may be small if you're looking local to you.

In my experience NO.
Police, Sheriff, Armed Security positions YES,
Most unarmed positions hired cheap - I'm assuming you want to raise a family.

Thanks for sharing!