The Messenger of Allah ﷺ ruled that when a mukatab slave is killed, his blood-money is calculated at the rate of a free man's blood-money in proportion to what he has paid toward his manumission.
أخبرنا محمد بن المثنى قال حدثنا وكيع قال حدثنا علي بن المبارك عن يحيى عن عكرمة
قضى رسول الله ﷺ في المكاتب يقتل بدية الحر على قدر ما أدى
[Its isnad is daif] Abu Dawud narrated it in the Book of Blood Money, Chapter on the Blood Money of a Mukatab, no. 4581, from the hadith of Yahya bin Abu Kathir through this route. It is also found in Al-Kubra, no. 7011, and Ibn Jarud graded it sahih, no. 982. Yahya bin Abu Kathir used the term "an" (indicating a possible break in the chain).