EXCLUSIVE

There's no doubt ... Brian Mulligan -- an international banking honcho -- was beaten to a pulp by the LAPD -- based on photos obtained by TMZ.

Mulligan -- the Managing Director and Vice Chairman of Media for Deutsche Bank -- is unrecognizable in the pics -- with severe nasal fractures and lacerations, a concussion, a fractured right scapula, and numerous contusions and abrasions.

Although the LAPD claims officers beat and arrested Mulligan after he became violent and threatening ... prosecutors declined to file charges. Our sources say prosecutors believe the photos are "clear evidence of excessive force." Indeed, Mulligan already filed a $50 million claim against the City of L.A.

TMZ first reported, Mulligan claims two LAPD cops beat him senseless after wrongfully detaining him ... claiming he resembled a person suspected of attempted car theft. Mulligan claims the officers took him to a hotel against his will and when he tried to leave officers brutally attacked him.

Mulligan's lawyers, J. Michael Flanagan and Valerie Wass, tell TMZ cops at the scene conceded Mulligan was NOT under the influence of drugs and they described him as “calm, lucid, and cooperative." They tell TMZ, "Mulligan had committed no violations of law and was not arrested. No drugs were found during a search of his person or his vehicle, and the officers found absolutely no evidence of drug use by Mulligan."