u/Supposed_too

What happened to Mr. Phillips at the end? When Mason unlocked the attic door either

• a) he was convinced by Sam that Mr. Phillips was a threat that had to be eliminated or
• b) he realized Sam was crazy and this was the last thing he did before leaving the cult.

If a (and Mason did say his brother killing his girlfriend was justified because "she was going to leave him") then how did they cover that up?

If b then why wouldn't Mr. Phillips tell his version of the story at his trial? It's not like Sam's going to take the witness stand to contradict him.