Okay.
So, I guess I need to steer this towards more 'magical' means, and less 'mystery' means, and thus, I'll have to be more deliberate in how I speak my black truths. Sorry about the wait you guys, but I needed some help.
Andrew - the college student - was the one behind the happenings and 'Iron Fist' Jack Rafferty... uh, I mean detective Damien was sent out to do an undercover investigation on a train. When things started to kick in, he moved into the 5th cart to check on Andrew, but he couldn't find him. When Andrew arrived back through the bottom floor staircase, he noticed Damien and killed him from behind. He then hid the body of detective Damien somewhere in the 5th cart.
...
Zack accidently inhaled a substance that was harmful for him.
Inhaled, because the key you found in Cart 2 had a very intense stench.
Zack did not inhale anything poisonous.
Damien is not a detective and was not searching for anyone.
This doesn't change the core of my argument. You only dispelled one possibility, and that was only an example. Here, let me generalize harder for you.
Zack was poisoned. Perfectly, humanly possible.
Repeat it in black!
"Zack was not poisoned."
FINE THEN FORMER WITCH. I SHALL GIVE YOU THE TRUTHS YOU HAVE BEEN DIGGING OUT OF ME.
Zack was poisoned. He absorbed the poison initially through his lips (not by ingestion!), thus causing it to spread through his bloodstream.However, the 'poison' is unique in that it is only used in the medical field to cure a completely irrelevant ailment - it's also very volatile to handle in the hands of a non-professional. Who would carry and do such a thing?
Also:
Regardless of intent, it's still possible for Patty and Jack to exist in one of the rooms we looked through and we missed their presence.
You would not miss Jack's or Patty's visible presence if they existed in the rooms you searched and moved through.
Olivia was sitting at the counter in the 3rd cart when Zack got his drink from Shandelise. She had a chance to put anything poisonous in Zack's juice while Shandelise was moving items from the shelf/drink cooler to the counter. Zack even said to Olivia that she poisoned him. It might still be a distraction, but let's go with this first.
Olivia put something poisonous in Zack's juice. That's how Olivia knew how to cure him.
...
Black truths are worse than red truths. They are a pain to read out and they cannot be seen when the sunlight shines on my screen from my window.
But wait!
Zack was the first one to open the juice bottle, thus making it impossible for the poison to be put into the juice before Zack drank it....also, I might be changing the 'dark black truths' to 'lame, but highly visible turquoise truths'.