Peace activist Carlos Arredondo has come to be known as "the man in the hat" and widely described as a hero for a viral image of him in a cowboy hat pinching the severed artery of a bloodied, wheelchair-bound victim in the aftermath of the Boston Marathon bombings. Arredondo is no stranger to tragedy: He became a prominent opponent of the Iraq War after his son, Lance Cpl. Alexander Arredondo, was killed in Iraq in 2004. His surviving son, Brian, committed suicide in 2011. Carlos and his wife Mélida, join DN to describe witnessing the Boston Marathon bombings and the immediate response to aid the victims.