Gainer, who is also a former Chicago cop and Illinois State Police director, watched the U.S. Capitol fall Wednesday to violent extremists, vandals and looters, most who were not from D.C.
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"What was unprecedented was the President of the United States at the other end of Constitution incited those people and really lit the match," he said.
Gainer has walked with presidents up the aisle for the State of the Union Address, and he's coordinated security for foreign leaders and major names, beginning in his hometown of Chicago.
"My first assignment in 1968 out of the Chicago Police Academy was the '68 Democratic Convention. And then the Days of Rage, when I was a very young police officer, 20-year-old police officer," he said. "So I saw some of the worst disorders, I saw some of the worst reaction by the police. I think we've improved over the years."
In Washington. He saw Capitol police making a terrible mistake.
"Capitol police did not have enough people in the proper position. So it would appear to me that the security officials of their House and Senate sergeant at arms and chief of the Capitol police. Apparently underestimated the violent crowd the size of that crowd and estimated their ability to manage them," he said.
Among the 146 arrests was David Fitzgerald of Roselle, who livestreamed as from the Capitol campus that he was being told he was under arrest. He pleaded not guilty to unlawful entry Thursday.
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Security experts said authorities shouldn't have been taken by surprise.
"It was clear, everybody knew that these protesters and quite a lot of them are coming to D.C.," said Olga Kamenchuk, security expert at Northwestern University. "There were there was definitely quite an aggressive, violent mob which was led into the heart of American institutions, democratic institutions, then into the capital. This is surprising. And this is concerning why this happened."
Illinois Congressman Mike Quigley (D-IL 5) also noticed the lack of security well before the start of the events.
"I walked around, I rode my bike around the Capitol the night before the morning of. I am no expert on security, but anybody can tell there wasn't enough there wasn't anybody outside. So now's the time to find out, was the National Guard, asked to be there?" he said.
Quigley and his fellow congressional representatives spent hours locked down to preserve their safety, and now they're looking for answers.
"This has been something that has been talked about for several weeks now. And they did not have with, in my opinion, the personnel, or the physical structures in place to keep us safe," said Rep. Lauren Underwood (D-IL 14).