Those two studies are enough to conclude that the NFL has no idea if anyone tampered with the ball. Any evidence that the Patriots were prepared to do so, withers on the vine of uncertainty.

You cannot claim there has been a homicide, investigate, find many circumstantially interesting pieces of evidence (gun, missing gun, ammo, shells, opportunity, motive) and then convict for murder if the forensic examiners cannot prove the deceased died because of a bullet.