As previously mentioned, all-star basketball player DeMarcus Tillman is seen with a Turd Burglar calling card in his wallet by multiple classmates. He's also highly suspected despite not having the glitch on his phone, because given his status as "Mr. Untouchable," he might have assumed he'd get away with pulling off a Turd Burglar-level stunt. There's ample evidence against him other than the card, too. First of all, he had access to the cafeteria because he's buddies with the cook and could've dosed the lemonade prior to the Brownout. He's also close with the English teacher whose classroom had the poop-filled Kurt Vonnegut piñata.
At the end of the day, DeMarcus is only responsible for one of the pranks, just like Jenna and Mr. Gesualdi: the piñata. He too was a victim of catfishing and sent "Brooke" pictures of his junk. Worried that if the photos got out his chances at playing college ball would be ruined, DeMarcus — who is basically this season's lovable dummy in the way Dylan Maxwell was in season one — agrees to the Turd Burglar's demands.