dr. catena says he's treated more than 2,600 people who are victims of al bashir's carnage. cuments the reign of terror and how dr. catena and the nuba people have turned the hospital into a symbol of their survival. we recently spoke with dr. catena via skype. >> in the operating room, we did 15 operations -- >> why sacrifice so much for so long? >> it's a good question. i think -- i think i take my role model as jesus christ. i think christ is really calling us to get rid of it, get rid of our baggage, whatever it is. i still have this drive and this zeal. god willing, as long as i have the strength and energy to carry on, i'd like to keep doing it. >> what is it about dr. tom? >> dr. tom is as close to a saint that i've met on the face of this earth. every morning he wakes up at 5:30, no alarm clock, after being woken up the entire night. >> he's always on call? >> always on call, no one else there. >> reporter: carlson and dr. catena attended college together, brown university, class of 1986. catena traded his degree and high-paying job offers to fulfill his calling to be