Yegads, if a spirit had a right to occupy the body of the one who killed it... wouldn't people at slaughterhouses be absolutely crazy with all the souls that could pack into them?? We'd be seeing way more cases of schizophrenia in jail, too...
Just gotta love how new age white-lighters love trying to scare you into with their "do bad things and be punished by karma" finger-wagging. Not.