Sergeant Keith Lewis, 31, died of a self-inflicted gunshot wound on Sunday night
Lewis was a member of the Army Special Operations Command at Fort Bragg, North Carolina
Police say Lewis fatally shot his pregnant wife Sarah Lewis, 34, who was due to give birth to their fourth child on Christmas Day, at their Fayettville home
He then turned the gun on himself after officers arrived at the scene
Sarah's relatives say her husband had suffered from PTSD and had threatened his wife in the past