"I had to kill men today. It wasn't a want to, it was a need. I had to, to get out of that situation I was in today," Eddie Ray Routh
said in a confession video that was played Monday in a Texas courtroom.
He is charged with murder in the February 2, 2013, shooting deaths of Kyle and Kyle's friend, Chad Littlefield, at a firing range.
Routh's lawyer admits his clievnt killed the men but contends he was insane at the time.
In the 90-minute confession tape, the defendant was interviewed by Texas Ranger Danny Briley.
Briley asked Routh what he did after he killed the two men.
"I fled. I didn't know what else to do. My adrenaline was so high. I didn't know what was right. I didn't know what was wrong. I mean, I know what was right now. I left, you know," Routh responded.
When asked what he would say to the families of his victims, he said: "I would tell them I'm sorry for what I've done."
Routh's answers to other questions were less intelligible. At one point, he veers off into talk about his soul.
"You can't just keep letting people eat your soul up for free, you know. It's not what it's about, it's about having a soul that you have in you for yourself. And there are tons of people that are eating on my soul right now," the defendant said.
Routh's trial comes just weeks after the release of the film about Kyle, a former Navy SEAL who claimed to be the deadliest sniper in U.S. history with 160 confirmed kills in Iraq. "American Sniper," directed by Clint Eastwood and starring Bradley Cooper, has grossed the most ever for a war movie.
Kyle's autobiography by the same name spent weeks on best-seller lists. He had already risen to fame through his book when he died, and was involved in charitable work to help former troops suffering from post-traumatic stress disorder.
Kyle and Littlefield took Routh, a veteran with mental problems, to the firing range as a kind of therapy.
The range is a small, remote part of the sprawling 11,000-acre Rough Creek Lodge, and the men were isolated.
A hunting guide found Kyle, 38, and Littlefield, 35, Kyle's friend, motionless and called 911. The men were dead when officers arrived.
Correction: Earlier versions of this report incorrectly described the military background of Chad Littlefield, who was killed with Chris Kyle. Littlefield was not a veteran.