If they can determine where the Brokaw address came from (which I haven't looked into - assumed it was gotten from the official abc news website), I might try to find a commonality as to who accessed those two websites in the appropriate timeframe, but first I would need to ascertain where else the addresses may have been listed in that exact manner.
But I'm not getting paid lots of bucks per hour, nor are you! :-)
Also, a librarian could have helped come up with the addresses. Or some other source entirely. But now I definitely lean toward the theory that someone copied them right off a computer screen by hand.
Maybe there are other letters in the system which might yield more clues.
I'm really, really curious why Daschle and Leahy were chosen. Arbitrarily? Perhaps.
On the Leahy/Daschle/Brokaw connection - our best bet so far is that it is issue+authority related. Leahy and Daschle both are for the International Criminal Court and NBC has commentary to that leaning. An ICC would be unfavorable to international terrorism IMHO.