into the attack raises serious questions about whether that has been investigated fully. here is cnn's nick payton walsh. i have to warn you this report contains graphic images that may be disturbing. >> reporter: the blast tore into the dense crowd. >> the very high bomb blast sound and then i saw a lot of hands, legs without their bodies. >> at least 170 afghans and 13 u.s. troops died after an isis suicide bomber struck outside kabul airport. the pentagon investigation of the attack released friday said everyone died in the blast. >> the single explosive device killed at least 170 afghan civilians and 13 u.s. service members. by explosively directing ball bearings through a packed crowd. >> reporter: a review unearthed this brief glimpse of the bomber. cnn spent four months investigating the incident