Not impossible, but if Krauss is a culprit then Doc automatically is too at a bare minimum.[/QUOTE
Yeah I laid out this theory earlier:
I think Krauss killing Natsuhi is the only option for T2, then faked his death and Nanjo 'confirmed' it. There can't be any master key shenanigans since Kanon confirmed all the servants had alibis, and Genji's key was destroyed.
I lean towards Krauss since he and Godha can lie about the room being locked in T1, which leaves the door open for Nanjo to do the killing in T1. Then Godha can kill Kumasawa in T5/T6 and fake his own death, so now all three qualify as Culprits.
But that means Jess also has to be a culprit since she 'confirmed' Godha's death, so we can have her kill Shannon in T4 to confirm Culprit status. Since there's two mystery people still alive at the end, and Nanjo and Jessica were both confirmed dead by narration, that leaves Godha and Krauss as survivors, after they killed off their fellow Culprits