I wouldn’t want "this character" to be a killer in "Original Sin"

Everyone is talking about the killer being the new captain or Tanya, but...

1. As one user here pointed out, it would be a big coincidence to have two serial killers in the same police department.
2. It's too obvious. Unfortunately, this is always the problem: a recognizable face = they’ll do something important, especially when they’re not part of the original show. But it’s better if they become victims of the killer, it would make for an unexpected twist.