Is it true that if you kill someone, they haunt you for the rest of your life?

My dad and I were talking and he was telling me of 3 instances where someone killed someone else and like they were haunted by that person. But the only person that can see the dead person was the killer, no one else could. It's like everywhere they looked, that dead person was there. I personally would go insane. My cousin killed my uncle over insurance money, and my cousin still sees my uncle to this day. A member of the KKK killed my cousin in the 70s and my cousin haunted him until the KKK member died.