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TMZSports.com Dana White is opening up on the betting scandal embroiling one of his now former fighters, Isaac Dulgarian, telling TMZ Sports what caused the UFC to actually reach out to the FBI! Dulgarian, 29, was a sizeable betting favorite (-250) over Yadier Del Valle at Saturday's UFC Fight Night, but ultimately lost by rear-naked choke in the first round. The result, combined with something that happened hours earlier, has raised serious alarm bells for the UFC honcho ... and that's why Dana decided to loop in the Federal Bureau of Investigation. White, for the first time, explained what went down on Saturday ... and in the days since. "About one o'clock that day, we're with a company called IC360 and they are the best bet monitoring company in the business. They reached out to us and they told us that there was some unusual action going on with that fight," Dana explained. "Do we know anything? We didn't, so what we did was we called the fighter and his lawyer and said, 'what's going on? There's some weird action going on in your [fight.] Are you injured? Do you owe anybody money? Has anybody approached you to, you know,' and the kid said, 'No, absolutely not. I'm going to kill this guy.'" "So we said, 'okay,' the fight plays out, and first round finish by rear-naked choke. Literally the first thing we did was call the FBI." Long story short, a bunch of money came in on Dulgarian to not just lose, but to do so in the first round by submission. On Tuesday, Dana told us he met with the FBI twice ... and had also spoke with Director Kash Patel. TMZSports.com We also spoke to IC360's co-founder, Scott Sadin, who runs the betting watchdog, about the signs they spotted leading up to Dulgarian's Fight Night scrap, which they felt were serious enough to contact the UFC. As for what's next, Dulgarian has been cut by the UFC, and the FBI is investigating.