'American Sniper' Trial: Widow Taya Kyle Cries as She Details Husband's Final Day

— -- The widow of "American Sniper" Chris Kyle could tell something was wrong when he spoke to her by phone from a Texas gun range shortly before he was shot and killed, she testified in court today.

Taya Kyle started to get worried when her husband didn't respond to a subsequent text message, and she said she learned her husband had been killed when a police officer showed up at her house shortly afterwards.

Pausing at points to wipe away tears during the first day of testimony in her husband's murder trial, Taya Kyle told the court, "I'm not nervous. I'm just emotional."

Eddie Ray Routh, now 27, the man accused of murdering Chris Kyle, 38, and Chad Littlefield, 35, Kyle's longtime friend, took notes throughout Taya Kyle's testimony.

Kyle said that her husband had never met Routh before Feb. 2, 2013, the day that they went to the Rough Creek Lodge gun range in Glen Rose, Texas, and he had decided to meet with him at the urging of Routh's mother.

Since retiring from the military in 2009, Kyle, who is recognized as the deadliest sniper in American military history, worked with veterans and regularly brought them to gun ranges.

Taya Kyle said that her husband believed that a week spent outdoors was more beneficial than a week in a hospital.

The 40-year-old mother of two, the first witness called in Routh's murder trial, revealed that Kyle, himself, had some difficulty adjusting to civilian life after a career spent largely overseas, noting that he drank and had night sweats. He eventually began to put on a little weight but he "still looked great," she said in court.

Testifying later was Chad Littlefield's mother, Judy Littlefield, who appeared so overcome with emotion that, at first, she seemed barely able to speak.

If her son was alive, she said, today would have been his 38th birthday. He was "a very good son," she added, noting that he called to check on her every day.

"Chad didn't talk much but was always watching to make sure people were safe," Judy Littlefield said.

She added that her son was not a veteran and first met Kyle when they were on the sidelines of their kids' soccer game.

The decision to have the women testify so early in the trial came largely because the judge ruled that no witnesses can be in the courtroom until after they have testified so they will not be affected by other testimony.

The trial began this morning with opening arguments from both sides, with District Attorney Alan Nash detailing Routh's alleged actions on the day of the shooting and defense attorney Tim Moore setting up his planned insanity defense. Routh faces life in prison if he is found guilty.

After both women finished their testimony, the manager of the shooting range, Frank Alvarez, told the court about the moment he was called to the range and saw people trying to resuscitate Kyle and Littlefield.

The prosecutor then began showing photos of the crime scene, including one that showed Kyle's dead body, during which Taya Kyle was seen shaking her head.

The man who first found Kyle and Littlefield's bodies, a responding police officer and a paramedic from the local fire department all testified this afternoon.