Paul in Hebrews makes it clear that through Christ the Levitical priesthood is no longer needed. Any of the practices associated with the priesthood are not binding. In addition, anything having to do with sacrifices are not binding since Christ was sacrificed once and for all.
I believe the 10 Commandments are part of the Moral Law. However, even murderers can attain forgiveness and salvation through Jesus Christ.
I agree that that the 10 commandments are also part of the moral law, the spiritual law, the royal law.
Murderers can also find salvation through Christ. I think it's not very likely though that a true Christian will ever murder someone physically.
We are on the same page after all. Regards. :-)