It used to be common to execute retainers to help out the king or queen in the afterlife. Sometimes just a few, sometime hundreds. Supposedly everybody who worked on Genghis Khan's tomb was executed, along with his entire funeral procession, and all their executioners, so nobody would know where it was. It was finally found, just recently.

I recall a story where an Egyptian priest tossed the royal mummy in the Nile and committed suicide in the pharaoh's tomb, thinking himself clever for it.