From the Time magazine interview
http://www.time.com/time/nation/article/0,8599,1179857-6,00.html

TIME: Your smiling mug shot: what made you think of that and what do
you think the consequence of that has been?

DeLay: Oh, I don't know. I said a little prayer. First of all, you only
get one take. It's a very humiliating thing, to be booked. And I said a
little prayer before I actually did the fingerprint thing, and the
picture. And my prayer was basically: "Let people see Christ through me.
And let me smile." Now, when they took the shot, from my side, I thought
it was fakiest smile I'd ever given. But through the camera, it was
glowing. I mean, it had the right impact. Poor old left couldn't use it
at all.