Young Thug's Gun Case Dropped by D.A.'s Office Due to Lack of DNA Evidence

2:10 PM PT -- According to legal docs, obtained by TMZ, cops were unable to find any DNA on the gun found in the same car YT was riding in. We're told because there were 3 people in the vehicle, investigators could not determine who the weapon belonged to, so YT will not face any charges.

The D.A.'s Office also cleared up details on the car accident that triggered the search. It was actually the police cruiser that was "unable to stop in time" before it hit Thug's Rolls-Royce.

Someone's gotta pay for what the D.A. deemed, "minor damage."

Young Thug's lawyer, Michael Goldstein, tells us, "I commend the District Attorney's Office for making the right decision after carefully reviewing the facts and body worn video over the past 9 months. The fact so much time and work went into this decision reinforces trust in our system of justice."

Young Thug will NOT be prosecuted in his L.A. gun case ... TMZ's learned the District Attorney is rejecting the case.

The D.A.'s Office tells us ... the case was rejected earlier this month due to insufficient evidence. YT's attorney, Michael Goldstein, confirmed to us the case is now closed. TMZ broke the story when cops busted Young Thug back in August -- a member of Thug's crew ran into a police car, which triggered a vehicle search. That's when cops discovered the weapons.

YT -- who was seen in handcuffs and escorted to a waiting cruiser -- was booked just after for carrying a concealed weapon in a vehicle ... a felony. The bust came on the night he was celebrating the release of his new album, "Slime Language" and his 27th birthday.

So, the arrest was quite the double whammy ... but now it's water under Thug's bridge.