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An autopsy has determined that Swamp People star Mitchell Guist died from natural causes.

The 47-year-old reality star collapsed Monday while working on a houseboat on the Belle River near Morgan City, LA.

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Mitchell appeared with his was brother Glenn on the History Channel show Swamp People -- airing Thursdays -- which chronicles the bayous of the Atchafalaya River Basin during alligator hunting season.

Speaking to the Baton Rouge Advocate, Glenn spoke about the loss of his brother. "He'd been building on a houseboat. He had just put it in the water this morning and was pushing it. That's when he went down," he said. "I still can't believe it. He was considered the baby of the family. I just can't believe it. He was as healthy as a horse."

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