Soulja Boy -- Secret Network of Cameras Finger Rapper's Bentley In Hit-and-Run Crash

Big brother is ALWAYS watching you ... and taking pictures ... just ask Soulja Boy, whose red Bentley was impounded by the LAPD thanks to incriminating photos taken by a secret network of police cameras stationed around L.A., TMZ has learned.

Our story begins on January 9, when a motorcyclist T-boned a red Bentley in Hollywood ... leaving the biker seriously injured ... but the driver of the Bentley -- who caused the crash by making a reckless turn -- fled the scene.

We're told a witness -- the victim's friend -- was so pissed off, he went back to the scene of the crime a few days later and nosed around, asking people if they knew who was driving the red Bentley. He struck gold at Roscoe's House of Chicken and Waffles ... when a valet told the guy he knew the car well ... it belonged to Soulja Boy, who frequented the area.

The witness went to police with the info ... and that's when things got Orwellian.

Turns out, the cops have access to a super-database of photographs taken by thousands of hidden cameras stationed on police cars, buildings and private vehicles all over L.A.. There are private companies that make money off the City by getting citizens and businesses to mount cameras for the database.

One law enforcement source tells us the cameras are constantly taking photos of cars all over the city -- and the average car is shot AT LEAST 1,000 TIMES PER DAY!!!

So ... the cops got the license plate number of Soulja Boy's Bentley, ran it through the database and BINGO ... a bunch of photos popped up showing the Bentley with damage that corresponded to the accident.

Soulja's Bentley is currently damage-free. Law enforcement sources tell us the operating theory is that the rapper had the car repaired on the sly to cover up incriminating evidence.

So cops got a search warrant and a judge agreed there was probable cause to believe the Bentley was involved in the accident, so cops went and impounded the car.

You're probably as shocked as we are about the cameras ... cops tell us they solve hundreds of crimes with these secret photographs. So even if you're a law abiding citizen, you probably still pick your nose, so heads up.

Cops would still like more evidence, so if you happened to be eating a delicious chicken and waffle combo on January 9, and witnessed the accident, give LAPD West Traffic a call.