Senators grill FBI's Comey on response to terror threats

The head of the FBI promised to learn from any missteps the bureau may have made leading up to last week's bombing in Chelsea. FBI Director James Comey defended his agency at a hearing on Capitol Hill Tuesday morning.

The Senate Oversight Committee questioned Comey about terror suspect Ahmad Khan Rahami. He said it was an active investigation. Investigators have not been able to interrogate Rahami because he is intubated and using a ventilator to help him breath.

However, after scouring over Rahami's cell phone, email and social media records and interviewing his wife and family, investigators have not come across any evidence that Rahami had co-conspirators who helped him with the bombings in Chelsea and Seaside Park, New Jersey, a law enforcement source told Fox 5.

Some senators told Comey the FBI missed opportunities to possibly prevent the bombings. Two years ago after Rahami returned from a year-long trip to Pakistan, a neighbor overheard Rahami's father call him a terrorist. The neighbor contacted a police officer, who in turn, contacted the FBI.

Federal agents interviewed Rahami's father and said he called his son a terrorist because he was acting like a thug and had stabbed his brother. At the time, the FBI said it did not question Rahami himself because he was in jail for the stabbing and his father had recanted his statement.

"We're going to go back and look very carefully at the way we encountered him, and we will find the appropriate form to give you that transparency about what we did well, what we could've done better, what we've learned from it," Comey said.

Comey also told the senators that federal authorities are concerned about violent extremists flowing out of Syria and Iraq intending to carry out attacks around the world.

"There will be a terrorist Diaspora sometime in the next two to five years like we've never seen before," Comey said.