house spokesman. >> we're working with our partners to investigate the allegations. it's absolutely the case in an environment, like the one you 1/2 syria, that proving chemical weapons use can be difficult. but we are engaged in a process of trying to investigate and verify these allegations. >> so it depends what the definition of chemical weapons is. that works to president assads a advantage, and at the same time it does give the white house some wiggle room when everybody goes back to the red line phrase. >> shepard: very valuable wiggle room. we're now hearing from the guy who says the boston bombing suspect carjacked him before they're wild chase and shootout with police. ahead, what he claims they told him and how he says he escaped. >> father and son canoe trip begins in horror after an alligator attacked the kid. an incredible story.