DALLAS (CBSDFW.COM) - Former head of the Dallas FBI office, Danny Defenbaugh is defending the agency's handling of the Orlando terror attack.
Defenbaugh ran the Dallas FBI office from 1998 to 2002 but he also oversaw some of the biggest terrorism investigations in American history.
He said it's likely other people will be implicated in the Orlando attack.
"I would not be surprised at all," said Defenbaugh. "Even in a lone wolf type of scenario, San Bernardino is a perfect type of example, there's the friend who helped him get the weapons."
Now retired from the FBI, Defenbaugh is closely watching his former colleagues work to build a case around Omar Mateen and anyone else who may be involved -- including Mateen's wife.
"She also admitted that she took him to get ammunition... she knew he was going to have a plan. You've got a lot of material support as far as I'd be concerned," said Defenbaugh.
From his key roles in the investigations into the Oklahoma City bombing and the attacks of 9/11, Defenbaugh knows the value of terrorism watch lists and defends the agency for removing Mateen's name twice in 2013 and 2014.
"It's page after page after page," said Defenbaugh. "It's very complex and you're talking about hundreds and hundreds of individuals literally on a daily basis where allegations are being made."
Defenbaugh said the FBI uses informants to back up allegations that lead to someone's placement on the list.
Once Mateen was removed, Defenbaugh said he would have been off the FBI's radar.
"If you're off the list -- you're off the list," said Defenbaugh, who defined his career in law enforcement fighting terrorism. But he said average citizens are still the best detectives when it comes to preventing attacks.
"We've become lethargic very quickly. In this situation some people supposedly saw a lot and really didn't say anything."
Defenbaugh last viewed the terrorist watch list about six years ago and it contained thousands of names.
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