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Congressman Bill Keating, D-Massachusetts, serves serves on the House Homeland Security Committee, and spoke to Secretary of Homeland Security Janet Napolitano this afternoon. The congressman said officials have not been able to identify if the attack is from domestic or international terrorists.
"There's a treasure trove of evidence in videos and witness statements," said Keating, adding that videos are still flowing in, and they are all welcome.
But even with the trove of videos, there appear to be few specific leads.
"I'm sure they are following different potential leads right now," said Keating, who used to be a district attorney of Norfolk County, Massachusetts.
If officials "are approaching anything that's promising, the last thing they want to do, is get that out into the public," added the former district attorney.
"One of the greatest advantages you have as an investigator, is when you have information, and the perpetrators you are trying to find don't realize you have that information," said Keating.