Defense attorneys presented testimony from a mental health expert on Thursday regarding the mental state of Eddie Ray Routh, who is accused of killing “American Sniper” Navy SEAL Chris Kyle and his friend Chad Littlefield. Routh has admitted to killing the two men but has pleaded not guilty by reason of insanity.

Routh is accused of shooting and killing Kyle and Littlefield at a shooting range in February 2013, where the two men had brought him to help work through the post-traumatic stress disorder (PTSD) Routh was reported to had suffered since serving in the Iraq war and in Haiti after the 2010 earthquake. Routh has admitted to killing the two men but has pleaded not guilty by reason of insanity.

On Thursday, defense attorneys called a forensic psychiatrist, Dr. Michael Dunn, who testified that Routh suffers from schizophrenia and was affected by it during the crime. According to a report by NBC News, Dunn reviewed years of Routh’s medical records and conducted six hours of interviews with him.

Dunn also testified about bizarre statements made by Routh, including his belief that various people — including Kyle, Littlefield, and his girlfriend at the time — were human-pig hybrids, and these pig creatures were taking over the world. Specifically regarding Kyle and Littlefield, Dunn said, Routh believed they were “pig assassins, hybrid pigs sent here to kill people.” Routh also told Dunn he believed his co-workers were cannibals and that a neighbor was a Mafia drug dealer.

Interestingly, Dunn questioned Routh’s PTSD diagnosis, testifying that Routh lied to him about how much he had been traumatized by his military service, and said that he did not believe that Routh ever suffered from PTSD.

Dunn also testified that Routh believed he needed to kill the two men out of self-defense, because he thought they were plotting to assassinate him, according to the Dallas Morning-News.

“He thought he was going to die if he didn’t take care of business and kill them first,” Dunn said. “If you are going to be killed, then you have the right to defend yourself. He defended himself…I’m not saying that’s logical. It’s logical in his sense.”

As Breitbart Texas reported, the standard under Texas law to prove an insanity defense is very high. Defense attorneys have presented evidence that Routh was hospitalized twice in July 2011, once in September 2012, and for the last time in January 2013, being released just a week before the killings. Over the years, he had been diagnosed with a psychotic disorder, depression, marijuana and alcohol abuse, and had been prescribed multiple anti-psychotic medications. Earlier this week, the defense had presented testimony from Routh’s mother, former girlfriend, and sister, who all testified about his alarming and bizarre behavior.

Kyle was a Navy SEAL and the most lethal sniper in American military history, serving four tours in Iraq. He received multiple commendations for his service before being honorably discharged from the Navy in 2009. A native Texan, Kyle was born in Odessa and returned to Texas after leaving the Navy. His memoir, American Sniper, was turned into a blockbuster film directed by Clint Eastwood and starring Bradley Cooper. To honor his life and service, Texas Governor Greg Abbott declared February 2nd to be Chris Kyle Day, as Breitbart Texas reported.

After Dunn’s testimony, the defense rested its case. The trial is scheduled to continue on Friday, for any rebuttal witnesses the prosecution wants to present, and closing arguments by both sides. Prosecutors are not seeking the death penalty, so Routh is facing a maximum sentence of life in prison without parole, if he is convicted of capital murder. Breitbart Texas will continue to follow this story.

Follow Sarah Rumpf on Twitter @rumpfshaker.