No one was armed, and it was WITHIN the defense perimeter of a federal building. Guards let these guys in ~ or there's a far more serious problem than is so far reported.
The US Marshalls Service would undoubtedly have picked this guy because they believe he'll do what "the man" says to do with no independent thought ~ (Which is a belief of his management, not mine. I've found any number of Hispanics over the years who are not terribly totalitarian).
So, a frameup? Need to see the directories on the cellphones, but most likely it was.
Here's how to do this if you ever need to know. Remember that every federal office of any kind is under a dicta that two things be done in setting up their office PBX. First, set it so it does not RESPOND WITH THE PHONE NUMBER. That's a no-no of the first kind. Secondly, make sure you deal with the issue of outside foreign contact or you'll be paying phone bills to Bulgaria for gambling interests and wholesale dopedealers.
Other than that they all operate the same way. Most PBX's use some variant of AT&T's Unix Operating System.
There's a problem area when it comes to these Congressional Offices. The guy answering the phone has a constituent on the line and the constituent expects the number dialed to show up in his screen ~ if it doesn't, he won't believe you're real.
So, Senator's field offices like this one usually aren't set up correctly. Likely they aren't set up to control the foreign calls either. Which is a pretty good indication the PBX is susceptible to hacking from OUTSIDE.
That means that what you want to do is dial the DIN, provide the correct signal to give you access to the PC that sets up the PBX, and just give yourself a line that only you can call. You set this line to answer to ALL lines in the office, and that way you are going to eventually pick up a bit of everything going on, but a whole lot of what the US Senator at the other end in DC is telling her field office.
DO NOT GO IN THE FEDERAL BUILDING.
You'll probably have to pay somebody to compute the DIN for you, but knowing that phone companies issue phone numbers to federal offices 20 in a block, just find the lowest sequential number that will call that office, and it'll be the one ending in "00" that's otherwise not used for calling.
If Senators were less arrogant and their staff people more honest this couldn't happen. GSA can do nothing about it.
These guys were up to something other than tapping the Senator's phone BTW. Modern digital systems are just nasty at the handset, and if you hit the blocks in the wireroom, you stand a good chance of finding the wire with the 210 hooked up to it. Lots of practical jokers out there.
This is not a job you do without knowing a whole lot about modern phone systems and PBXs. I would recommend reading through this website to find out how hard a job you've got ahead of you ~ except with almost any US Senator's office ~ http://www.gphone.com/Hosted-PBX/Hosted-PBX.aspx?cid=hosted-pbx-faq