Tomogui - Vol. 2 Ch. 8

[MangaDex]

 

[Akikako]

the guy seems intelligent because they are all idiot in that class...

 

[Ominous]

Guy gets his fingerprints on all the phones and not one gets sent to a lab for investigation. Miyata's phone wasn't even sent out despite the teacher recovering it. Only way this makes sense is if sensei has an ulterior motive or is just dumb for the plot. Oh and chloroform works instantly here, too.