More info needed on Secret Service

Now, we're bloggers in Connecticut so we're not use to all the D.C lingo so I can really use some help here. Since my blog traffic is going through the roof, I have a few questions that might clear up a few things.

Secret Service vs. Capitol Police

Now, someone just dropped me a message indicating that the Secret Service is based in Maryland and therefore, their plates would be Maryland and not D.C. Is this correct?

Capitol Police: High level senators have Capitol Police protection with the police often dressed in suits. Is this true? If it is, it might explain the DC plates and the ease in which the person took the pictures and was able to ask a couple of questions before team Joementum approached him.

Many questions and I need answers. Come on you big DC bloggers, put your heads together and get back to me.

UPDATE: A blogger claims it might be Hillary. I CAN NOT CONFIRM THIS but I think he's on to something here.

UPDATE 2: It wasn't Hillary. I don't know what Brigham was talking as I simply stated what he posted and I never made a prediction of Hillary stumping for Joe. I had no idea about the idenity of the mystery person and was looking for answers to some questions.

Ugh...that's the internet for you. It's all good, where just trying to get to the bottom of the story.