"A 9,000 year-old case of human decapitation has been found in the rock shelter of Lapa do Santo in Brazil," according to Science Daily.
"[The archaeological site], located in east-central Brazil, contains evidence of human occupation dating back to ~12,000 years ago. In 2007, researchers found fragments of a buried body, Burial 26, including a cranium, jaw, the first six cervical vertebrae, and two severed hands at the site. They dated the remains back to ~9,000 years ago using accelerator mass spectrometry. The researchers found amputated hands laid over the face of the skull arranged opposite each other and observed v-shaped cut marks on the jaw and sixth cervical vertebra."