It was the ring, of course. The ring. Had it truly made its way down Van Zieks's esophagus to nestle itself in his stomach, it would've caused quite a bit of damage during its journey. There was no sign of any of that. I daresay, no human would dare to swallow something quite so pointy and prickly to begin with. [Not even Holmes.] Watson could very well have planted it on the body. Or, err, inside the body.

[He leans towards Naruhodou, peering down at the photo over his friend's shoulder.]

That big bushy bearded fellow over there? He arrived in England on the same day Gregson was found dead? [Hm. But isn't this guy one of Mikotoba's companions? Actually, now that he thinks about it...] All those years ago, when Mikotoba and Asougi were in England for their exchange project, wasn't there a third student? Someone who'd insisted so fiercely upon their friend's innocence in court that he was almost incarcerated himself?