Eddie Ray Routh (pictured) is accused of fatally shooting "American Sniper" Chris Kyle and Chad Littlefield at a Texas gun range in February 2013. Reuters

The “American Sniper” prosecution rested Tuesday after three weeks of testimony and evidence was presented to a Texas jury. Eddie Ray Routh is on trial in Stephenville, Texas, for killing the former Navy SEAL Chris Kyle and Kyle's friend Chad Littlefield at shooting range in February 2013. Here are five quick facts about the prosecution’s case, courtesy of the Associated Press, the Dallas Morning News and KXAS Texas.

1. Routh admitted he shot Kyle and Littlefield at Rough Creek Lodge shooting range.

Routh has not denied that he shot and killed Kyle and Littlefield. In fact, he said he was agitated by the fact that his victims did not talk to him on the ride to the range. "I had to take care of business. I took care of business, and then I got in the truck and left," Routh said in a phone interview with a New Yorker magazine reporter, according to the Dallas Morning News.

2. Routh pleaded not guilty.

Even though his defense team is going to claim the accused was insane at the time of the killing, Routh claimed he had to shoot Kyle because the former Navy SEAL would have shot him otherwise. “If I did not take down his soul, he was going to take down mine,” he said about Kyle in a videotaped confession shared in court Monday. “I had to kill them before they killed me,” Routh told the New Yorker reporter. He also expressed remorse. “I’d tell them I’m sorry for what I’ve done,” he said. “If I could have done it differently, I would have done it differently.”

3. Routh may have suffered from post-traumatic stress disorder (PTSD).

Routh is a former Marine who served in Iraq and in Haiti after the tragic 2010 earthquake. He started to take anti-psychotic medication, but the prosecution claimed he knew the difference between right and wrong when he killed Kyle and Littlefield. When he was arrested, Routh told Lancaster police Officer Flavio Salazar that he felt unstable. “I’ve been so paranoid and schizophrenic all day. ... I don’t even know what to make of the world right now. I don’t know if I’m insane.”

4. Routh said he was pressured to shoot at the range in rural Texas.

Another factor that reportedly led Routh to fire the fatal shots was that Littlefield allegedly pressured Routh to fire his gun. "Are you gonna shoot? Are you gonna shoot? It's a shooting sport. You shoot," Routh said in the phone call. "That's what got me all riled up."

5. Routh’s defense lawyers wanted a mistrial.

The prosecution told the jury at an earlier date that drug paraphernalia, including a vial that could be used to fill a hypodermic needle to inject illegal drugs, was found at Routh’s home. It turns out that the vial did not come from Routh’s home and was put in the evidence kit by the technician who performed tests on the evidence. When his lawyers asked for a mistrial, the judge denied the motion and the jury was informed the information was given in error and to disregard the erroneous evidence.

The trial of Chris Kyle has garnered national attention after the former Marine’s memoir, “American Sniper,” was turned into the Oscar-nominated film starring Bradley Cooper. If convicted, Routh will face life in prison without the possibility of parole.

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