Possibly. Only the case with Firefly and Dan is up in the air. Dan could have been affected and died before we found out, or Firefly could have been really good at hiding whatever was up with her.

[Or, you know, it could just be a regular murder for the motive of apples.]

But with Jing Yuan, Hawke, and now Neverah taking on signs of the seven deadly sins, I don't think it's a coincidence anymore.