But, Professor Harris, I mean, again, what's the answer to the argument that if that is indeed the group of people where crime is most present, then that's the appropriate group of people to subject to this level of scrutiny?

NPR: The Difficulties Of Proving Racial Profiling

"We will go to the ends of the Earth to identify the subject or subjects who are responsible for this despicable crime, and we will do everything we can to bring them to justice, " Mr DesLauriers said.

BBC: Boston bombings: Obama condemns 'act of terrorism'