Anyone who's lived or been around the block for any period of time in LOF (Land of Frowns) knows the deal here.
One / a group of Somchais hit on Farang girl
Farang guy defends girl
Group of Somchais get tooled up
Somchais follow girl and guy
Somchais rape girl
Somchais smash both the Brits to death.
BIB display gross incompetence/xenophobia from the beginning of the investigation, allowing the Somchais to escape from the island.
Hardly rocket science is it?