this is napalm. that is something that is indicative and characteristic of the napalm. are there countless numbers of explosives? there are dozens of types of explosives. reporter: investigators begin to narrow the possibilities with field tests like this one. a quickly analyzed residue. this orange points to a c-4 bomb. anthony says the severity depends on timing and placement and there isn t always visible proof. is it possible that an explosive can go off on a plane and there be no residue? it s possible that there could be no residue left. reporter: here s why. look at the wreckage from the metrojet crash, much of it consumed by fire. if you have melting aircraft parts, melting aluminum, it s mixing with the other parts that it could easily disguise any evidence of an ied. reporter: anthony says it s
those statements in contradiction to egyptian statements. what are investigators looking for? kyung lah is outfront. reporter: the power of a bomb aboard a passenger plane. this demonstration by the u.s. attorney s office shows the end result. coming through the office. reporter: the beginning tracked by forensic bomb expert thomas anthony. is this a classic c-4 explosion? it is. less push and more force. we have less residue than a low explosive. reporter: starting with a c-4 bomb, he walks us through the impact of several types of bombs and the telltale signs they believe behind. reporter: the residue from the black powder coming from a central point, look at the edges here. the edges are very, very different. they have this sort of almost coral-like look to them.
the beginnings tracked by forensic bomb expert thomas anthony. this is a classic c-4 explosion? it is. less push and more sort of force like that. we have less residue than a low explosive. starting with a c-4 bomb, a type of plastic explosive, the civil aviation security measure caulk wauks ugh floug the impact of several types of bombs and the telltale signs they leave behind. the residue of the black powder coming from to a central point, look at the edges here. the edges in the black powder very, very different. they have this sort of like almost coral-like look to them. this is napalm. look at all the residue of the napalm that was left behind. that s something that is indicative and characteristing of the napalm. are there countless numbers of explosives? there are dozens of types of explosives.
critical to have forensic proof of an aviation investigation and only a lab can sift out evidence of this. just as important, piecing together clues beyond the wreckage knowing who and when would have placed the explosive device aboard the plane. there are so many electronics that we can buy off the shelf that can be programmed to activate hours, days, weeks, months in the future. so if this is indeed a bomb, how long before there is that tangible evidence and this russian airliner disaster? anthony says it could be days, months. the evidence here could prove critical if they can narrow down where in the wreckage they look for that evidence. kyung, thank you. with me now, david susie along with former cia operative bob baer. you heard kyung s report, even if they don t find traces of
reporter: anthony says the severity of a bomb on a plane depends on many factors like timing and placement, and there isn t always visible proof. is it possible that an explosive can go off on a plane and there be no residue? it s possible that there could be no residue left. here s why. look at the wreckage from the metrojet crash. much of it consumed by fire. if you have melting aircraft, parts melting aluminum, it s mixing with the other parts that it could easily disguise any evidence of an ied. anthony said it s critical to have forensic proof in an aviation investigation, and only a lab could sift out evidence from this. but just as important, piecing together clues beyond the wreckage, knowing when and who may have placed an explosive device aboard the plane. there are so many electronics that we can buy off the shelf