Jeff Manning was KILOD in Afghanistan.
Jeff's parents divorced when he was three, and his father remarried and moved to Arizona. He married to Natalie Manning until his death and served in the Army Rangers. The two had a son Owen Manning, whom he never met his son as he was born after his death.
During 1x17, Natalie loses her wedding ring and is diagnosed with broken-heart syndrome. During the same episode she goes to his grave and leaves the wedding ring to him.
Captain Jeffrey Manning was killed in action during Operation Enduring Freedom on February 2015.