Desiigner's Driver Served Time for Illegal Steroids

It's becoming clearer than ever who owned the steroids found in the SUV in which Desiigner was riding ... because TMZ has found a criminal trail leading right to the driver.

Scott Siegel was driving the SUV when another driver called 911, claiming someone in the vehicle had pointed a gun at him. Although no gun was found, cops retrieved 302 pills from the SUV's console ... all of which turned out to be steroids.

Although Desiigner and everyone else in the SUV have been charged with illegal possession of drugs, we've learned steroids have been Siegel's thing for years. In fact, he was convicted in 2010 of distribution and possession of anabolic steroids and served 3 years in federal prison.

On top of that, Siegel appears in the movie "The Wrestler" in which he sells steroids to Mickey Rourke's character.

Although all the evidence points to Siegel as the person in possession of the steroids, the D.A. is not backing off the drug charge against Desiigner, who was in the backseat and claims he had no idea drugs were in the vehicle.

Law enforcement tells us it's common in New York for cops to arrest everyone in a vehicle in which drugs are found, and down the line the D.A. drops charges against the people to whom the evidence doesn't stick.

Seems it's just a matter of time before Desiigner is cleared.