Happy MLK day to the dude that was the body guard to Comey and is now for Mueller

And to all those that are doing all they can for justice, equality, and the protection of the Constitution. I was curious as to who that black dude who always walked behind/ and sat behind Comey when he came to Congress to testify, and now walks behind Mueller when Mueller ventures outside (as their body guard), is. Do the bodyguards work under the Justice Department, or are they part of the Secret Service? I was just curious. His job of protecting Mueller from physical harm by any number of psychos out there may be the most important as the Russia investigation goes on. He seems to be a guy that you don't wanna mess with. He is always about 2-3 steps behind his protectees. Happy MLK day to all.