welp just got stabbed in the back
Also tfw there's two 9 doors, so classy Zero. Anyway given they killed both Lotus and I, which is 8+5=13, and how they seemed to be acting alone, they must really want one of the 9 doors for themselves. But the only combinations for that are 6+7 (June+Seven), 3+2 (Santa + Snake), and 1+4 (Ace+Clover). Snake may be dead but I dunno maybe someone snatched his bracelet when everyone split up, that's what happened to the captain in the Axe ending, so that's possible and means Santa could have done this alone. I can't really see June and Seven cooperating admittedly and there's not much grounds for it because they were both alive prior and separated, plus the culprit is one person and while June/Seven could've killed the other, it doesn't feel very solid if you ask me.
Clover did go missing, which makes me think her death is quite possible, but it's hard to say how relevant Ace could be based on what was seen and said before Junpei got murdererdered.
That said, the only knife I remember was in room 4, although June was in that room either way iirc, so maybe she was up to something, but it's hard to say, but it still begs the question regardless of which pair is most relevant; who pushed Snake through the door???