Amr bin Dinar (may Allah have mercy on him) narrates from his teacher that Sayyiduna Umar (may Allah be pleased with him) gave a ruling concerning a Muslim who had killed a dhimmi: If he did this in a fit of anger, then take 4,000 as blood money; and if he is a habitual criminal, then kill him.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15929