Chad Littlefield's family said Wednesday a connection between Eddie Routh and Littlefield’s brother made it even harder to watch Routh’s long trial.
The family spoke with a gag order lifted that had blocked relatives and witnesses from talking with reporters.
Littlefield’s brother, Jerry Richardson, said he was a high school teacher in Midlothian when Routh attended school there.
“He and a few other kids were discussing what they would do if they ever killed someone,” Richardson said. ”And his comeback was, I would claim insane and be off in three to four months.”
Richardson and Littlefield’s parents, Don and Judy Littlefield, spoke in an exclusive interview with NBC News.
They said they tried to be sympathetic to former U.S. Marine Routh’s claims of post traumatic stress disorder, but trial evidence showed Routh never saw combat and lacked sufficient trauma to justify the disorder.
Prosecutors argued Routh’s heavy drug and alcohol use were more to blame for his odd behavior.
It took the Erath County jury of 10 women and two men about two hours Tuesday night to reject Routh’s insanity defense and find him guilty of murder. Judge Jason Cashon immediately sentenced Routh to life in prison.
Littlefield's family made victim impact statements to Routh after he was sentenced.
“We have to suffer this senseless loss just because of the choices he made,” Judy Littlefield said.
His relatives said Chad Littlefield was a quiet man who listened more than he spoke. Testimony showed Routh to be a constant talker and Routh’s confessions heard in the trial show he was insulted by Littlefield’s silence.
“It almost seems like he took it out on Chad but had to kill Chris because he knew Chris would shoot him,” Judy Littlefield said.
Chris Kyle, subject of the movie “American Sniper” about his life, and Littlefield had gone with Routh to the Rough Creek Lodge shooting range in Erath County on an outing that was supposed to be therapy for Routh at the request of his mother.
Richardson said details heard in the trial were hard to accept.
“When they draw the lines from dot to dot throughout this case, it sickened us,” he said. “How could someone have done that to two great men?”
Kyle’s widow, Taya, issued a statement on Facebook.
"God Bless the Jury And good people of Stephenville, Texas," the statement said.
Routh was still listed as an inmate at the Erath County Jail Wednesday, but he will soon be transferred to state prison to begin serving his life sentence.
NBC 5's Bianca Castro contributed to this report.