Travis Mullis, a Texas man convicted of stomping his 3-month-old son Alijah to death in 2008, was executed by lethal injection on Tuesday evening. Mullis waived his right to appeal and referred to his execution as a form of 'assisted suicide', expressing remorse for his actions and apologizing to his son’s mother and family. He had a history of mental illness and admitted to sexually assaulting and murdering his son after reaching a 'breaking point.' Mullis was the fourth inmate executed in Texas this year and the 16th in the U.S. this year. His execution was part of a series of five executions scheduled within a week across the U.S., including another execution in Missouri on the same day.