Unfortunately the Kenya Police were not independent. I am sure Troon released similar notes when he concluded Biwott and Oyugi were the chief suspects.
Troon was the only independent nexus in the investigation. An experienced detective for Scotland Yard.
Put another way, no Kenyan police investigator, would in their right state of mind point at Biwott. Anybody old enough then knew it was suicidal.
That is why they had to come up with a ridiculous suicide theory.