Halakhah for Sanhedrin 104:20

The commandment on the court (beit din) to kill with strangulation one who is liable: That we have been commanded to kill the transgressors of some of the commandments of the Torah with strangulation, as it is stated (Exodus 21:12), "He who strikes a man and [that man] dies shall surely be put to death." And this one of "One who strikes a man" is one of the ones whose death penalty is with strangulation. Since it is written about it, "[he] shall surely die" - and in the explanation, they, may their memory be blessed, said (Sanhedrin 52b), "Any death penalty stated in the Torah undifferentiated is only strangulation." We have learned that those that are liable for the death penalty do not have repayment, as it is stated (Exodus 21:11-12), "there is no money. He who strikes a man and [that man] dies, etc." - Mekhilta.