A chilling video shown in court showed police placing Routh into a squad car moments after authorities chased him down a Texas highway. Earlier that day in February 2013, authorities say he gunned down two men who were trying to help him at a firing range: Chris Kyle
, subject of the hit film "American Sniper," and Kyle's friend, Chad Littlefield.
In the video, Routh is breathing heavily and teary-eyed.
An officer asks if he's OK. Routh replies: "I'm just so nervous about what's been happening in my life today. I don't know what's been happening. I've been so paranoid 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."
At times, Routh appears agitated in the video. He squirms around the back seat. Other times he rests his head with his eyes closed.
The small arsenal of weapons Kyle brought to the range that day was shown to the jury, which included five long rifles and several handguns, including one of Kyle's rifles labeled "American Sniper."
According to defense attorneys, Routh, in his psychotic state, thought he was walking into a showdown on the range
Another piece of evidence prosecutors presented Tuesday: a recording of a conversation Routh had while behind bars.
From inside the jail where Routh has spent the last two years, he spoke with a writer from the New Yorker Magazine three months after the shootings
Routh can be heard saying he was annoyed at Kyle and Littlefield.
"So we're shooting pistols here huh? Hmmm, OK, Again, that's pretty much saying duel motherf*****."
Later in the interview, he's asked what sparked the killings. Routh blames Chad LIttlefield for not shooting with him.
"I was like what the f*** are you even doing here man? This isn't a spectator sport, it's a shooting sport, you shoot. And that's what got me all, you know, wired up."
He also said: "I took care of business and then I got in the truck and left."
Routh's lawyer admits his client killed Kyle and Littlefield, but contends he was insane at the time.
Prosecutors have described Routh as a troubled young man, but they argue he wasn't insane; they say these are the actions of a cold-blooded killer.
Routh's mother takes the stand
Taking the stand for the defense, mother Jodi Routh painted a different picture, describing her son's history of mental health problems.
After his time serving in the military, she said, "he was no longer his happy-go-lucky self."
His first stay in a VA mental ward was for three days in 2011, she said. Then he returned again, against his will, and spent weeks in the facility. When he was released, she said, he was on nine different medications, including mood elevators, anti-psychotic medications and sleep aids.
Jodi Routh said she had asked Kyle to help, telling him that her son had been diagnosed with post-traumatic stress disorder.
She told Kyle that her son had been hospitalized multiple times, but did not tell him that he'd also threatened to kill himself and his family.
"Do you regret not sharing that level of detail?" prosecutor Jane Starnes asked.
"I just wanted to get help for my son," the mother replied.
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 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.