Carl Hoffman, who visited the tribe and police in the years after his death, wrote extensively on the topic of the disappearance.
He claims that he does know how Rockefeller died, according to those who lived in the area.

Apparently, when Rockefeller swam to make it to land, he washed ashore in nothing but his underwear and was immediately met by familiar faces: the Otsjanep warriors.
But while Rockefeller was known to have been a respectful and kind man to the tribe, they weren’t in the mood for visitors, or so it seems.
So, when they saw him lying helpless on the shore, one of them allegedly stabbed him with a spear through his ribs and the rest cannibalised him.
While Hoffman can’t be sure why they decided to kill him that day, he believes it was in retaliation for an incident which saw Dutch colonists burn huts and murder high-ranking tribesmen just one year prior.
While we might never know what really went on, it’s a good theory.