"Dancing With the Stars" The Nancy Grace Fart Mystery

Nancy Grace definitely cut a rug on "Dancing with the Stars" last night ... but did she also cut the cheese???

Listen closely to the clip of Nancy yakking with Brooke Burke after she waltzed to "Moon River." You'll hear what sounds like a fart escaping from someone. As far as we can tell, there are only three possible culprits.

Nancy Grace claims she's been FRAMED in the "Dancing with the Stars" fart mystery ... and tells TMZ an "investigation" is underway to find out who REALLY dealt it.

Grace -- who was doing a post-dance interview on the show last night when someone let it rip -- tells TMZ, "As an ear witness on the scene, I can absolutely exonerate Tristan, myself and Brooke."

She adds, "However, the rest of the cast -- seated just inches away -- all remain under grave suspicion. The investigation continues."

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