“Here’s my conspiracy theory - pilot takes a break, and co-pilot dumps the fuel...causing the fuel slicks that have been found. The deed is done, and nobody can wrestle the controls from him to save the plane. And they just fall out of the sky...but a little north of the fuel slicks.”
How about not contacting the tower?
Jet fuel that is dumped at altitude evaporates.
It never reaches the ground.
It would have to be a heavier oil to make a slick. If it was in the water because the fuel tanks broke up upon impact, an oil slick could be there. They could tell by analyzing the residue.