GALVESTON, TX --DNA tests show that a Southeast Texas man convicted of capital murder in the 2008 death of his 3-month-old son sexually assaulted before stomping him to death. Texas Department of Public Safety DNA analyst Tanya Dean testified about the tests during the penalty phase of the trial of 24-year-old Travis James Mullis. Mullis was convicted Friday of stomping on his son's head to stop him from crying. Galveston County prosecutors are seeking the death penalty Wednesday for the death of son Alijah Mullis. Jurors only alternative would be life imprisonment without parole. Court-appointed defense investigator Gina Vitale testified that Mullis' mother neglected him until he was adopted upon her death by her half-brother. That uncle later went to prison for sexually molesting Mullis when he was 6.