Dis gon b my personal mystery.
Someone was trying to kill Richard, who was originally trying to use this bathroom, but failed when the punks showed up. Zack was just an unlucky victim.
Andrew stole a vial of substance from Olivia's medkit, then applied it to the faucet when nobody was looking.
Why Andrew? Well it couldn't have been Olivia for several reasons. Andrew was the one though who collided with one of the businessmans in the beginning, so he has a connection point. The white truth also lives if my theory is incorrect.
Witch, answer the question: Who collided with Andrew? Terry or Richard?