The prosecution in the trial of the killer of Chris Kyle rested Tuesday, and on Wednesday the defense for Eddie Ray Routh began. Kyle, a former U.S. Navy SEAL, is the subject of the Oscar-nominated film “American Sniper.” He and friend Chad Littlefield were fatally shot by Routh on Feb. 2, 2013 -- as the shooter admits. He has pleaded not guilty by reason of insanity, and Routh's attorneys quickly began to build the case that the former U.S. Marine is insane.  

The prosecution left off Tuesday with a video of Routh from the day when Kyle and Littlefield were killed. “I’m just so nervous about what’s been happening in my life today. I don’t know what’s been happening,” he told officers after he was placed in a police car, according to CNN. “I’ve been so paranoid and schizophrenic all day. I don’t know what to even think of the world right now. I don’t know if I’m insane or sane.”

The defense claimed Routh felt he was walking into a life or death situation with Kyle and Littlefield, not just going to a gun range at Rough Creek Lodge and Resort, as the men had planned. Routh, attorneys said, felt he had to shoot the two men -- it was him or them.

When Routh’s mother Jodi took the stand, she said she asked Kyle to take her 27-year-old son to the gun range to help him, and that he had been diagnosed with post-traumatic stress disorder. She said she told Kyle that Routh suffered with mental health problems, but didn’t tell him he had threatened to kill himself and his family. "I just wanted to get help for my son," his mother said.

After the killings, Routh drove to his sister Laura Blevins’ house. She testified that he seemed to be in a “daze” when he arrived, the Dallas Morning News wrote Wednesday. "He said he took their souls before they could take his. I asked him what he meant by that, and he said they were out to get him," Blevins said. "When I was looking at him, he kind of looked like he was out of it, almost in a daze or something, and when I told him that I loved him, there was something in him that understood that.”

Blevins' husband described Routh as "incoherent."

Routh’s girlfriend, Jennifer Weed, testified that he was unstable the night before the slayings. "I asked him if he was seeing things, and he said, yes," Weed said. "He definitely had paranoia about the government out to get him."

If Routh is found guilty of capital murder, he could spend the rest of his life in prison without parole.

Follow me on Twitter @mariamzzarella