Among the 3,000 people Hillary Clinton drew to a rally in Florida last night was the father of the man responsible for killing 49 people at the Pulse nightclub in Orlando on June 12, according to a local news report.

A Clinton campaign official tells NPR that the rally in Kissimmee, Fla., on Monday was open to the public. NBC affiliate WPTV identified one attendee as Seddique Mateen, the father of Omar Mateen, who was killed in a shootout with police after carrying out the deadliest mass shooting in modern U.S. history.

"This individual wasn't invited as a guest, and the campaign was unaware of his attendance until after the event," the Clinton campaign official said in an email exchange.

Not only was Mateen at the event, but he was also positioned behind Clinton, so he was visible in photos and video of the candidate's speech. Mateen is recognizable, in part, because he did so many interviews after the nightclub attack.

After the Clinton rally, Mateen again did a television interview. "Hillary Clinton is good for United States versus Donald Trump, who has no solutions," he said to WPTV.

Here's WPTV's description of finding and interviewing Mateen, which is a story in itself:

"WPTV happened to notice the man, who has a mustache and was wearing a red hat, behind Clinton. It was Seddique Mateen, the father of Orlando mass shooter Omar Mateen...." 'We've been cooperating with the federal government, and that's about it,' he said. 'Thank you.' Mateen didn't want to answer any other questions, but just hours later, we ran into him by chance at a rest stop on the way back to West Palm Beach. He wanted to do an interview and show us a sign he made for Clinton." 'Hillary Clinton is good for United States versus Donald Trump, who has no solutions,' he said."

Check out WPTV's full story for more quotes from Mateen.

Last month, Clinton met privately in Orlando with family and friends of those killed at Pulse. She also paid a somber visit, laying white roses at a memorial at the club. Even at the start of last night's rally, Clinton paid tribute to the victims and their loved ones.

There is no reaction yet from Donald Trump's campaign, but Clinton opponents are already seizing on it.

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