These things always remind me of the old junk yard dog. Laying asleep, someone kicks it, and it gets up barking, biting at anything around, and the kicker is already gone. You see all the armored cars, rifle toting NG or swat, and guards everwhere. Whoever set off the bombs is either at home watching TV, or on a bus heading for somewhere else. But there is a need to ACT vigilant. Now we will have to watch all the marathons, ball games, and other gathering places; maybe next time it will be the starting point, or midway, not the end.
Are bomb sniffing dogs trained to detect BP? or just nitro and such? My thinking is that blakc powder was used because someone didn't know how to get dynamite or detonate it. That goes to the theory that it is a local nut, not Moslem trained. I doubt that the idea was, as the TV said, to NOT knock down buildings and maim instead of kill; whoever built the best bomb he knew how to, and maybe he found out that reloading powder doesn't make a good explosive, so used a couple cans of Goex.