David Barajas, 32, faces a life sentence if he is convicted of shooting Jose Banda, 20, in December 2012. Banda was driving with a blood alcohol level of about twice the legal limit when he rear-ended Barajas's truck, crushing his sons, David Jr., 12, and Caleb, 11.
District Judge Terri Holder asked family members to remove the blue pins with the boys' photographs. The pins had the words "Forever in our hearts, David and Caleb Barajas.
The courtroom was packed with members of both Barajas's and Banda's families.
"This is a difficult case for everyone involved," she said. "I know everyone in here has lost someone they love."
Assistant Brazoria County District Attorney Brian Hrach acknowledged Banda was responsible for the boys' deaths.
"Jose Banda did a stupid thing, he made a horrible decision by drinking and driving," Hrach said in his opening statement. "But he did not deserve a public execution."
Barajas' truck had run out of gas near his home outside Alvin. Witnesses told investigators they saw Barajas walk to his house after the crash.
While no one could see if Barajas had a weapon, police later found an empty holster at the house. Witnesses reported hearing gunshots.