Mujahid (may Allah have mercy on him) narrated that Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) ruled that for one who kills in the Haram, or in a sacred month, or while in ihram, the full diyah plus a third of the diyah is due.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16135