aluminum. >> the fragment samples contained steel and brass. the steel had the exact same combinations of iron, manganese and chromium. in the brass, copper and zinc were found in identical amounts. and all the samples had equal amounts of cerium, part of a compound used to ignite an oxyacetylene torch, a common item in machine shops. >> we examined all of them and could see the pattern that regardless of where they came from, they were basically the same kind of metal fragments, machining fragments. >> this proved that both arlene jensen and stephanie dittrick were killed by the same man. >> the science is starting to really catch up to the bad guys now. >> a serial killer was on the loose in the seattle area. he had to be stopped before he could kill again.