Justin Bieber Paparazzo Death -- Photog's Mom Sues CHP ... Cops Killed My Son

The mother of the paparazzo who was struck and killed by a car back in January -- after chasing Justin Bieber's Ferrari -- is suing the California Highway Patrol, claiming it's the cops' fault her son is dead.

Vickie Guerra -- mother of 29-year-old photog Chris Guerra -- claims in her suit a CHP officer abused his authority by ordering Chris to unsafely cross a busy street.

TMZ broke the story ... Chris had been photographing Bieber's white Ferrari while CHP deputies were writing the driver -- Lil Twist -- a ticket for speeding on the 405 Freeway.

In her lawsuit, Vickie claims the CHP officer noticed her son snapping photos and in a threatening manner, gesturing with his gun, the cop ordered Chris to keep his distance by crossing the street.

Vickie says her son obliged and was struck by a car traveling in excess of 40-50mph. Vickie says her son flew over the first car and was immediately run-over by a second car.

Vickie is suing the CHP and the State of California for unspecified damages. She's also suing the driver of the car that hit Chris.