Eric Knysz is charged with first-degree murder in the killing of Trooper Paul Butterfield II during a traffic stop last September.
The 43-year-old trooper was the son of a state police officer, a high school cross country champion and a competitive runner at the University of Tennessee.
Sarah Knysz said she and her husband were transporting guns when Butterfield stopped them. She struck a plea deal and is to testify against her husband.
Jury selection began Tuesday morning, and Mason County Circuit Judge Richard Cooper named 11 women and three women to hear the case. Cooper said he'll give jurors instructions Wednesday before lawyers deliver opening statements.