inside that truck which is cobalt 60, to make a dirty bomb. first now to the active search however. the mexican officials are looking for the stolen truck and alerted the international atomic be energy agency in geneva which put out an international advisory. u.s. law enforcement officials tell cnn the government has skens cores at border crossings. agents are carrying portable devices which kk scan vehicles. it s not clear that the thieves were after the cobalt 60 inside. they say the truck also carried waste and scrap material which may have been the reason the truck was skarthed but it may have been that the cobalt 60 was inside. this material is used for brain imaging and to treat cancer, wolf. it is highly radio active. how difficult would it be to weaponize this material? experts are telling us it would be fairly difficult. it s usually in lead casing which it is in this case. it s not easy to remove it from