גֹּאֵ֣ל הַדָּ֔ם ה֥וּא יָמִ֖ית אֶת־הָרֹצֵ֑חַ בְּפִגְעוֹ־ב֖וֹ ה֥וּא יְמִיתֶֽנּוּ׃
The avenger of blood shall himself put the murderer to death; when he meeteth him, he shall put him to death.
Read kabbalistic (mystical) interpretation of Numbers 35:19: and classical mystical sources.