Gladys Did It!
She killed Otis ...
called it.
I guess she had her reasons.
sharethought it was the ts woman
You can't persuade fanboys. You'd be better off trying to convince a wall. ~CodeNamePlasmaSnake~
I though it was Cotton. We see her leaving, with serious face, I think looking for her gun.
She had heard Star and Otis on the phone.
But still, what a murder mystery! Did not expect that ... :)
Well it could have been anyone with whom we saw with a weapon, their motive is of course obvious reasons.
Or even Alexandra could have done it. That would be a big twist. She's not expected and she did follow him after getting off the elevator.