emerging is that they were deadly but crude. a federal law enforcement official with knowledge of the boston bomb investigation tells cnn, the bombs were hidden in bags. >> among items partially recovered are pieces of black nylon which could be from a backpack and what appears to be fragments of bebes and nails thought to be contained a pressure cooker device. >> reporter: it is likely but not certain that a timing device was used to set off the bomb. and doctors say that the bomb was meant to kill or maim as many people as possible. >> due to the number of sharp objects that we found inside people this bomb possibly had metallic fragments in them and we removed pellets and nails. >> reporter: mike buchard is a former top official with the