[ams6110]

Without doing any research I'd assume that either there was an investigation and insufficient evidence was found, or that there was not because there was not even probable cause to begin one.

To think otherwise is to believe in a conspiracy between Boeing, NTSB, FAA, and the FBI or whichever law enforcement agency would have jurisdiction.

The FAA has some conflict of interest in its mission, but the NTSB does not and is generally considered to be the premier accident safety investigation group in the world.

[lutorm]

The NTSB is in the business of determining causes of accidents, though, not of assigning blame and certainly not of assigning criminal liability.