That doesn't make any sense,and if it does, that should be only in US
lets say i wanna kill alot of ppl
I leave my door unlocked, open a window and start yelling and calling for desperate help, someone is walking by the street, hears me, get in to help me out and I shoot him. I can keep doing it everyday since I won't be breaking any law
Or how about inviting in someone that is trying to sell me something at the door, once he gets in bang, he's dead and he won't bother me more
Or lets say wanna break all killing records:
Call pizza delivery, once they get inside my property for delivery, bang he's dead
Mail yourself something, once the delivery man gets in, bang
Once you have a nice pile of boddies call the police and report robber, once they get in bang! **** another robber disguised as police
Eventually you'll have to stop killing and let them take the bodies
I'm sure i can find some other ways if needed