House Homeland Security Committee Chairman Mike McCaul (R-Texas) told reporters that he's worried if the FBI investigation takes too long, the bombers could have the chance to flee the country.

"Everyday that passes, it gets colder," McCaul said. "As a federal prosecutor, the first 24 hours of a murder case are pretty important."

The forensic tests on the bombs could be completed as early as today, which will give officials more specific information about the bomb maker, McCaul said.

"That's going to tell us a lot," he said. "Hopefully they execute search warrants and hopefully find these guys."

"The terrorists are still out there. I know flights outbound of the United States are on high alert. But every day that goes by it's more difficult to find them," he said.

Updated at 2:04 p.m.