This is a bad tendency in people to blame biharis for everything. The truth is that crime in, say delhi, is usually done by haryanvis and white collar crimes by punjabis as well - basically delhi is a very corrupt place.when i was in bangalore, i saw that locals and villagers were into crime. so, bang alos was never a crime free place. biharis were hardly involved in this anywhere. of late, i can see that certain bihari groups do petty crimes but i have also seen that the police in NCR, in order to not do the hard work, blame everything on biharis. in fact, they also arrest bihari rickshawpullers randomly wihtout any proof while serious haryana gangs are operating with no conscience even against killing.
i'm sure something similar is on in bangalore and mumbai as well. notice the new year molestation incident. i don't know how many of the perpetrators were biharis but i do know that the non-biari police did not arrest a single perpetrator on the spot.