It seems really obvious that it was either extra judicial "justice" that the guards and other parties conspired on, or he was put into a witness protection program for giving up contacts and this fact is so critical to take down trafficking rings that everyone must play along with him being dead.

I can't imagine other rational outcomes, he was high profile, and I absolutely expect Americans to think the vigilante justice is justifiable here, and lots of people would openly support that too. If he had compelling enough information on high profile individuals though, I can absolutely believe a deal was cut for his life, and his death faked.