Defense attorneys started to make their case today in Eddie Ray Routh’s trial with family members testifying in court that he suffers from post traumatic stress disorder among other things. 

Roth is accused of killing "American Sniper" Chris Kyle and his friend, Chad Littlefield, in February 2013 at a shooting range. 

Shepard Smith reported that Routh's sister testified in court today that her brother went to her house immediately after the shootings. Routh's sister said that "the person who came to my house was not the person I know as my brother." 

Judge Andrew Napolitano weighed in on "Shepard Smith Reporting" today, stating that there's no dispute Routh is the killer. 

"There's no dispute in this case that he pulled the trigger, and that he killed Chris Kyle and the other victim," Napolitano said. "The issue is what's going on in his head."

Napolitano shared that it is the burden of the defendant to prove insanity in the state of Texas.

"In the rest of the United States, it is the burden of the government to prove sanity," he stated. "That's not an academic difference, it's a real difference. It means he has to come up with all of the psychiatric evidence and the government has to rebut it."

He remarked that Routh's lawyers have not done that yet and that they are laying the framework with the testimonies from Routh's family, describing his "bizarre behavior."

Napolitano added that the prosecution will likely play Routh's confession tape repeatedly during the trial in an attempt to convince the jury that Routh is not insane.

"I think the evidence of guilt is overwhelming," Napolitano said. 

Watch the video above to hear the rest of the discussion on "Shepard Smith Reporting."