Justin Bieber Reckless Driving Case -- The Plot Thickens

Justin Bieber's security people have told cops ... they have video showing that Tyler, the Creator -- NOT JUSTIN -- was behind the wheel at the time the car was being recklessly driven on Memorial Day ... this according to law enforcement sources.

Here's the problem -- if Justin really was the one who was recklessly driving, the security people could be part of a conspiracy to hang Tyler out to dry.

TMZ posted video of Keyshawn Johnson Friday ... in which Keyshawn says he saw Justin behind the wheel of his Ferrari in the driveway of his gated community. We're told 3 other witnesses also saw Justin behind the wheel.

Keyshawn tells TMZ ... when he confronted Justin in his garage ... Justin said he wasn't driving during the wild ride and got into the driver's seat in the driveway to park the car into the garage -- which is a tricky maneuver in a low-riding vehicle.