Kyle's funeral service is scheduled for Tuesday. He will be buried at the Texas State Cemetery in Austin after a 200-mile funeral procession.
Iraq War veteran Eddie Ray Routh, 25, has been charged in the Feb. 2 killings of Kyle and his friend Chad Littlefield at a North Texas gun range. Routh is being held in Erath County on $3 million bond.
Taya Kyle spoke kindly of Littlefield during the service Monday, saying he was the "effortless, no expectations" friend that her husband needed.
Many said before Monday's service that they didn't know the 38-year-old Chris Kyle. Air Force Master Sgt. Kevin Phillips said he came from his Fort Worth home to honor "a brother in arms."
Esperanza Meza, who is in the Texas State Guard, said: "I'm here to pay my respects to him, and also for all of those who have fallen while serving this country."
Travis Cox, director of FITCO Cares, has said the men apparently had been helping Routh work through post-traumatic stress disorder.
Kyle, Littlefield and Routh arrived together at the Rough Creek Lodge shooting range, about 50 miles southwest of Fort Worth, authorities say. Routh later fled in Kyle's truck and went to his sister's home.
According to a search warrant, Routh told his sister and brother-in-law that the men "were out shooting target practice and he couldn't trust them so he killed them before they could kill him." Routh's sister called the police, describing her brother as "psychotic." Routh was arrested after a short police chase.
Routh's brother-in-law told authorities that Routh had recently been diagnosed with post-traumatic stress disorder.
One of Routh's attorneys, J. Warren St. John, said his client had been released from the Dallas Veterans Affairs hospital against his family's wishes just two days before the shootings.
Littlefield's funeral was held Friday in Midlothian. Afterward, Littlefield's relatives said the outing with Routh was intended to be therapeutic.