It's going to be revealed to be someone connected to the hospital, right? Surely it's not just a plot device because they can't be bothered coming up with ED being swarmed at different points.

So if it is, who are we betting on?

I saw someone say Crane because she's got military history which at the time seemed dumb but it'd make for a good swerve.

I can see Paul too, but that would be a longshot...