since 2011, the president of sudan, omar hasan al bashir, has been waging a brutal war against his own> omar hasan al bashir, genocide, he lost control of the southern part of sudan so he has this desire to get this part of the country back because it's naturally resource rich. >> he's willing to kill his own people so that he can have the land? >> that's right. this is all a program to discourage, to oppress these people, and to push them out of this region. >> reporter: dr. catena says he's treated more than 2,600 people who are victims of al bashir's carnage. carlson documents 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 en