That's what's so frustrating in all this. Aruban LE don't leak details of what evidence they have. Not even the defendants are told what the cops know, and for a while, they don't have access to a lawyer.
If one of the Kalpoe bros. or both decided to tell the truth about what they know or saw, or heard from Joran, and gave statements to the cops, would that allow them to go free? Why would they get their passports back if presumably, they'd have to testify at some court proceeding against J?
Scenario B: Why couldn't Joran claim the bros. did it and though he tried to save N, he was overpowered. He could claim he lied because they threatened to kill him or say he'd done it. This is hard to swallow considering J's size and clear domination of the Kalpoe bros. His mom sniffed that they weren't J's 'real friends', but 'more on the fringe'. The Kalpoe's weren't really good enough for her son. (Colonial mentality -- People of color aren't 'our sort').
We may never get the true story, unfortunately, but I do wish the Kalpoes would talk as I think it would shed a lot of light on things and help piece together some of the bits we think we know about.