I just don't see any modern groups really going out of there way to indoctrinate any specific set hand to hand system into what they do, not in the era of the gun anyway. I know the Sparrow gang in the phillipines had there hitmen train on close range quick draws and suprise ambushes for assassinations and my bet its more of that type of training you would see if orgainzed from within.
A few nasty hand to hand strikes picked up from an older mentor here, a few knife tricks picked up from another guy with experiance there, combative shooting advice through gang family and practice, other nasty bits spread throughout, that type of thing.