Shanti Parva 165.47

The man that knowingly kills such a woman incurs double the sin that follows from Brahmanicide. A drinker of spirituous liquor should live spare diet, practising Brahmacharya vows, and sleep on the naked earth, and perform, for more than three years the sacrifice next to the Agnishtoma. He should then present a thousand kine with one bull (to a good Brahmana). He would then regain his purily by doing all this.