This, despite prior warnings from both Russia and Saudi Arabia on the older of the two. EVEN SAUDI ARABIA WARNED US? Apparently, at least these two countries have better intel on what's going on here than all of our intelligence agencies combined.
We've all watched TV shows that show facial recognition systems being used by the authorities. These systems find matches in a matter of moments. Now, of course, these results are dramatizations. The actual systems take a long time to find a match - a very long time. But, they do work and work quite well - even if the results are not 100% effective all the time.
You can purchase state-of-the-art facial recognition software which you can install on your computer for a few hundfed dollars.
So, since the government has (I'm guessing) much more sophiosticated systems than "normal folk", I'm guessing it could have found these two bombers fairly quickly. After all, at least the older one was on a "terrorist watch list".
Therefore, one must conclude that:
a) The government is incompetent
b) The government didn't really care that much
Or, something that it doesn't want us to know. And, if this is the case the government must really have a low opinion of its citizens' IQ. There are news articles all over the place describing the ever expanding "cluster" of those involved in these bombings - not just the two.