U.S. Rep. Bill Keating (D-MA), a former District Attorney from Norfolk County, Massachusetts and current member of the House Homeland Security Committee

The Boston Marathon is the oldest marathon in the country, he said, with runners coming to compete from more than 100 nations. “So it’s that kind of symbol that a terrorist would look at,” he said. “And also, it’s Tax Day. It’s April 15th, and if it’s a domestic terrorist that hates the government and wants to rebel, that’s a symbol as well.”