So I have to ask, since the "student" didn't come forward, did the prof, have his permission to do so? IF this happened, there are so many holes in this story, it sounds custom crafted to fit the template of the moment,(see, they're watching you, watching what you read, what you say, see, nobody is safe,)
Also, this bit, " They brought the book with them, but did not leave it with the student, the professors said. Williams said in his research, he regularly contacts people in Afghanistan, Chechnya and other Muslim hot spots, and suspects that some of his calls are monitored.", seems odd, why do we need to know they kept the book? Gratuitous crap to show how evil agents won't even let the poor guy get his info for his lousey little term paper? IOW, if this were the case, perhaps they were visiting other students who had requested this book, or it may be entirely false. Seems like the prof, (who "told" the paper, that a student "told" him, that the agents "told" him....) might actually be more in the sights of this investigation (if there is one) than the students. The book itself is not rare or hard to find. Given the prof's background, it seems most likely. But the student also has some interesting things in his background. And yeah, just who is the student afraid of? Hmmmmm?
Did the student (he is so afraid) tell the professor, because the visit was about the professor? Or did he tell him something like, "we are so busted." Inquiring minds want to know. This smacks of lies by the prof. Getting his spin out first. I am as nervous as anyone about giving the gov't rights to monitor private activities without a good reason. But the good reason might be here.
Maybe they were Communist recruiters posing as Homeland Security agents.
Make at least as much sense as the other drivel in the story.