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ANDERSON, Ind. – FBI Director James Comey said Monday the man responsible for killing 49 people at an Orlando nightclub had been investigated by the FBI beginning in 2013.

“Our investigation involved introducing confidential sources to him, recording conversations with him, following him,” Comey said.

Ultimately after 10 months, the FBI closed its preliminary investigation.

“The bottom line is the FBI doesn’t have enough resources to, or the legal authority to, maintain open investigations on everybody they talk to,” John Pistole said in an interview with FOX 59, former FBI deputy director.

Pistole, also former head of the TSA and counterterrorism efforts for the FBI, is now president of Anderson University, but still advises Homeland Security officials as a member of the Homeland Security Advisory Committee.

“There’s thousands of people the FBI talks to every year,” he said. “The question is if they pose a threat. If that judgment is made, then the investigation will continue. If the judgment is made they don’t currently pose a threat, or there’s not an indication they pose a future threat, then the investigation will be closed. And that’s what it sounds like happened here.”

The FBI said Omar Mateen was on a terror watch list during the federal investigation but was taken off after federal agents found no credible tie to terrorism or that Mateen ever broke the law.

Pistole said the nightclub shooting underscores the new threat in terrorism — homegrown extremists attacking soft targets – places across the country most vulnerable to attacks.

“As Director Comey has said, there are pending counterterrorism investigations in every state in the country,” Pistole said. “So the fact that Indianapolis or here in Anderson we have not been targeted is not an indication it’s not a future threat involved.”

Late Monday, Rep. Andre Carson (D-Ind.) received the latest intelligence briefing as part of the House Intelligence Committee.

“It is clear that we are in a time when soft targets are being targeted like nightclubs and we are living in times where the uncertainty is growing,” Carson said. “Our intelligence services and our law enforcement in state and local, FBI, CIA, Homeland Security, they are constantly looking at potential attacks and threats.”

Pistole said preventing future attacks comes down to priorities and resources for the FBI, Congress and Americans between proper surveillance and civil liberties.

“If we continue to see attacks like this, I think it would be appropriate for the FBI director James Comey to seek additional resources,” Pistole said. “As I imagine he will.”