There's 3 possibilities here, 1 of you is lying
Option A: You're lying and you're scum. (more likely)
Option B: Yo Tan Wa is lying to frame you and is scum himself (Unlikely cause he'd be trading 1:1 for a townie, not that worth it as scum)
Option C: Yo Tan Wa is lying about the investigation but is Town too (A gutsy play and also pretty dumb, he'd be throwing a blind accusation that might get 2 townies killed)