You get branded as crazy conspiracy theorist before you know it. The best position to take is therefore: "I don't trust the authorities on this, and don't need a theory to justify myself".

The safest assumption to make in such situation is, that Aaron was suicided, one way or another. People, who stand against corrupt authorities often end up this way. It is most unfortunate, that criminal investigators can't provide credible evidence to the contrary. Movie cops always put their careers on the line if that's necessary to fight crime. In real life, however, there are mortgages to be paid.