DA who prosecuted celebs for cocaine posession arrested for cocaine posession

The deputy D.A. who prosecuted Paris Hilton and Bruno Mars scored coke 3 to 4 times a week in the crack den of Las Vegas... this according to the police report obtained by TMZ, and we've learned he's been locked out of his office and is about to get fired.

David Schubert, who was busted Saturday night, had gone to a notorious area of Vegas Saturday night. Schubert, who was driving a BMW, stopped and cops observed a male get inside his car.

The two began driving and cops were suspicious, after the passenger got out of the car, went into a an apartment complex and came back out. When Schubert allegedly committed a traffic violation, cops made their move and stopped the vehicle. The passenger got out and ran, and was subdued after a foot chase.