When player has 5 or more kill counts, he/she will be defined as murderer. Its name and tag will be red-in-colour.
When a murder is being killed, he/she will be received any penalty immediately. But if his/her corpse is being carved, and chopped-off head is being taken. Player can carve his/her head using dagger or blade. Murder will receive a 0.1 deduction on all skills.

Q&A

Q: What if I killed a murder 10 times and took his 10 of his heads, can I carve them all in a time?
A: Yes! He will receive totally 0.1x10 skill deduction.

Q: When I killed a murder when he was red, but he had dropped his murder counts to below 5 and he became blue. Can I still carve his head to make skill deduction penalty on him?
A: Yes. As long as the time when you kill him during he was a murderer.