Carpenter is convicted of killing Moureen Gathua, 24, and their 6-month-old son Kyan Gathua-Carpenter in June of that year.
At the time, Carpenter was a U.S. Marine based at Camp Pendleton.
Video: Kwame Carpenter arrested in June 2015 in deaths of his wife, infant son
Father detained in connection to deaths of baby, child's mother in OC
Investigators said after an argument with his girlfriend, he stabbed her and their son with a kitchen knife and then fled the scene.
He was found and arrested the next day following a short police chase.