Defendant Eddie Routh made a court appearance in Stephenville, Texas, earlier this month for a pre-trial hearing.
He reportedly found his daughter in bed with the teen. The father had a gun and asked the teen to identify himself, police said, according to the report.
His daughter reportedly told her father that she did not know the teen and that the two were not in bed.
His autobiography became immensely popular but also controversial.
Before Chris Kyle's death, former wrestler and Minnesota Gov.
"The communities that we reside in have been tremendous, and the people down in Texas have just been fantastic in their support of Taya and the kids," he said.