Noah Kahan Fan Poop Incident Not Being Investigated by Police

Noah Kahan's mystery concert pooper won't be answering to the law after all ... because cops tell TMZ they aren't investigating the crappy incident that left fans gagging.

Philadelphia Police tell TMZ ... no one ever filed a report over the viral bathroom blunder ... so there's no investigation underway despite the internet frenzy.

As we reported, the chaos unfolded during Noah's Friday show at Philadelphia's Citizens Bank Park, where a woman was accused of pooping in her seat before allegedly tracking the mess through the crowd. Noah even weighed in afterward on X ... begging fans not to crap their pants.

Now, Monday on "TMZ Live," we spoke with Chelsea Dubow -- the unlucky fan who captured the now-viral video -- about what she says happened.

Chelsea says she didn't actually witness the alleged act herself ... but after her video exploded online, she connected with the woman seated directly behind the accused fan, who claimed the whole thing was intentional. We think that's "smearsay" ... a joke she happily embraced.

Chelsea did add one detail she says she witnessed firsthand -- her husband stepped in the aftermath ... making the whole ordeal a whole lot harder to shrug ... or rather wipe off.