Plato, Laws 866b

τοῦ τελευτήσαντος γένει ἐγγύτατα ἐπεξίτω μὲν φόνου τῷ κτείναντι, διπλᾶ δὲ πάντα ἔστω τὰ τιμωρήματα τῷ ὀφλόντι. ἐὰν δʼ ὁ προσήκων ἐγγύτατα μὴ ἐπεξίῃ τῷ παθήματι, τὸ μίασμα ὡς εἰς αὐτὸν περιεληλυθός, τοῦ παθόντος προστρεπομένου τὴν πάθην, ὁ βουλόμενος ἐπεξελθὼν τούτῳ δίκην, πέντε ἔτη ἀποσχέσθαι τῆς αὑτοῦ πατρίδος ἀναγκαζέτω κατὰ νόμον. ἐὰν δὲ ξένος ἄκων ξένον κτείνῃ τῶν ἐν τῇ πόλει,

to fulfil the times appointed in exile, then the next of kin to the dead man shall prosecute the slayer for murder, and in case of conviction all the penalties shall be doubled. And should the nearest relative fail to prosecute for the crime, it shall be as though the pollution had passed on to him, through the victim claiming atonement for his fate; and whoso pleases shall bring a charge against him, and compel him by law to quit his country for five years. And if a Stranger involuntarily kills a Stranger who is resident in the State, whoso pleases shall prosecute him under the same laws;