Where Did Laughner Fire From?

Why would there be any confusion about what direction Giffords was shot from? Isn't this unusual?

Doctors initially thought the bullet entered the back of the skull and exited the front, but after reviewing X-rays and brain scans, two outside physicians brought in by Giffords' medical team now believe that Giffords was likely shot in the front of her head.

I couldn't find any article that discussed where the shooter was in relation to Giffords-- seems like it should have been clear what direction she was shot from... but is there another shooter they are trying to cover up?

(thanks to jh for the link)