Chief Warrant Officer Christopher Royal survived the 2009 massacre at Fort Hood, Texas, with two bullet wounds to his back. The slugs left him with nerve damage that numbs his left arm and leg and sends streaking pains "shooting up and down my back." And it's left invisible scars as well -- post-traumatic stress that has hurt his ability to perform his duties as a computer specialist and left him unable to feel safe in his own country. "I really feel more comfortable downrange. I really do," said Royal, who served in Iraq four times and in Afghanistan once. "I think I would be more comfortable living in Iraq right now than living in the United States." At 41, he's preparing to leave the Army at the end of September. But first, he's going to testify against the man accused of opening fire on his fellow soldiers at Fort Hood, troops who were preparing to ship out to Afghanistan and Iraq. Prosecutors will start presenting their case against Maj. Nidal Hasan on Tuesday in a court-martial at Fort Hood, outside Killeen, Texas. Royal, who escaped the gunfire only to go back into the processing center in an attempt to tackle Hasan, will be one of the witnesses against him. "I had escaped without being wounded," Royal said. "I got about fifty meters (yards) in the parking lot, and then I said, 'I can't let him get away with this.' And I wasn't even thinking that I didn't have a weapon. I just knew that I couldn't let him get away." Hasan, an Army psychiatrist, is charged with 13 counts of premeditated murder and 32 counts of attempted murder. Prosecutors hope to show that the devout Muslim had undergone a "progressive radicalization," giving presentations in defense of suicide bombing and about soldiers conflicted between military service and their religion when such conflicts result in crime. A military judge ruled last week that the prosecution can introduce evidence of Hasan's Internet searches on jihad and the Taliban in the days and hours before the rampage, but has deferred a ruling on whether they can introduce other materials. Hasan will represent himself in his court-martial. He told the judge, Col. Tara Osborn, that he plans to call two witnesses during the proceedings. The case has been delayed repeatedly since it was initially set to begin in March 2012, most notably after an appeals court delayed the case over the question of whether the beard Hasan has grown while in custody could be forcibly shaved. Meanwhile, Royal copes with his pain and stress by taking near-scalding baths and running, including a roughly 70-mile jaunt from Fort Hood to Austin. But he says he can't deal with crowds any more -- not even on the post. "I don't even really go to the mall anymore," he said. "I can't take my child to Disneyland, because I can't deal with it." As for Hasan, he said, "I have forgiven him." "I can't hold that grudge," Royal said. "It's just too much. I won't allow him to consume any more energy for my life than he has already done, and so I have released him. "I have forgiven him completely," he said. "It's not up to me to punish him. His punishment will come." The-CNN-Wire ™ & © 2013 Cable News Network, Inc., a Time Warner Company. All rights reserved.