Snag in Bank Media Honcho Cop Brutality Lawsuit -- He's A Bath Salts Addict

The Deutsche Bank honcho who claims LAPD officers beat the holy hell out of him back in May contacted police 2 days before the alleged beating and confessed he was addicted to bath salts.

TMZ obtained audio ... recorded moments after Brian Mulligan flagged down a Glendale police officer on May 13th -- claiming a helicopter was following him.

FYI -- Mulligan is the Managing Director and Vice Chairman of Media and Telecommunications for the bank.

In the audio -- released by the LAPD -- the officer can be heard explaining to Mulligan that there were NO helicopters, and Mulligan was just imagining them.

Mulligan then admits he had recently taken a hallucinogen called "White Lightning" -- a commercial name for "bath salts" -- and appeared to be under the effects of the drug.

When pressed, Mulligan says the last time he took the drug was "two weeks ago" ... but admitted he'd used the drug 20 times since purchasing the stuff at a head shop. He said the first time he experimented he felt like his face was melting off.

Eventually, Mulligan calmed down ... and the cop let him go.

As we reported, Mulligan claims LAPD officers beat him to a bloody pulp on May 15th -- just two days after the helicopter conversation -- and filed a $50 million claim against the City of L.A. The bath salts revelation could torpedo his case because a jury could well believe Mulligan was out of control and LAPD used reasonable force to subdue him.