After the shootings, Routh left the shooting range in Kyle's black pickup truck, Bryant said, first going to his sister's home in Midlothian, about 25 miles southwest of Dallas, where he told her and her husband what he had done. Routh left, Bryant said, and the couple called local police.
Routh arrived at his home in Lancaster, about 17 miles southeast of Dallas, at about 8 p.m. Police arrested him after a brief pursuit.
Kyle's nonprofit, FITCO Cares, provides at-home fitness equipment for emotionally and physically wounded veterans.
"Chris was literally the type of guy, if you were a veteran and needed help, he'd help you," said Cox, the director of FITCO Cares.
Cox described Littlefield as a gentle, kind-hearted man who often called or emailed him with ideas for events or fundraisers to help veterans. He said he was married and had children.
"It was just two great guys, with Chad and Chris trying to help out a veteran in need and making time out of their day to help him. And to give him a hand. And unfortunately this thing happened," Cox said.
Bryant expressed a similar understanding of the situation. The sheriff said Routh's mother "may have reached out to Mr. Kyle to try to help her son."
"We kind of have an idea that maybe that's why they were at the range for some type of therapy that Mr. Kyle assists people with. And I don't know if it's called shooting therapy, I don't have any idea," Bryant said.
Lt. Cmdr. Rorke Denver, who served with Kyle on SEAL Team 3 in Iraq in 2006, called Kyle a champion of the modern battlefield. Denver wasn't surprised that Kyle apparently used a shooting range to help someone with PTSD.
"For us, for warriors, that's a skill set that has become very familiar, very comfortable for us," said Denver, a lieutenant commander in a reserve SEAL team. His book "Damn Few," about training SEALs, will be released this month. "So I actually see it as kind of a perfect use of Chris' unique skill set and expertise of which he has very few peers."
Craft International, Kyle's security training company, had scheduled a $2,950-per-person civilian training event at Rough Creek Lodge called the "Rough Creek Shoot Out!" for March 1-3. The price included lodging, meals and shooting instruction. Kyle was scheduled to teach the first class, called "precision rifle."
Kyle is survived by his wife, Taya, and their two children, Cox said.
Sherman reported from McAllen, Texas. Associated Press writers Andale Gross and Erica Hunzinger in Chicago contributed to this report.