Slaughter House Yogi's Diner

Alleged criminals and drug users are being abducted by a cult that wears real animal heads as mask. As part of their ritual they consume parts of their victims' bodies. The remains are never found. Tri-State Police departments gather at their meeting spot, Yogi's Diner. Where the best grilled chicken in the USA is served.... What would it take to apprehend the cult? And what evidence could the police have that hasn't been digested?