How The NRA Impeded The Boston Bomber Investigation

Question: What is the probability that the 26 year-old police officer at MIT would still be alive today had the FBI (etc) been able to trace the gunpowder used by the 'Marathon Bombers'? With that time-critical, unnecessary delay in mind, understand this: "The NRA opposed using taggants" (ID/tracing agents), "saying they would contaminate some explosives used by gun hobbyists, like old-fashioned gunpowder called black powder and the newer smokeless powder. It said people who liked to fire antique rifles or who loaded their own ammunition would have to use less accurate gunpowder."
http://www.nationalmemo.com/how-the-nra-impeded-the-boston-bomber-investigation/2/