I'm definitely not a legal mind but can they actually make a PI cease investigating this?
They may not be able to make him/her stop investigating, but they can kill him/her and that will cause him/her to stop investigating. These are very evil, wicked, and powerful individuals. They kill , or cause to be killed whomever it pleases them to kill. With absolutely no concerns, worries , or cares of being brought before the bar of justice.
A thug?