The well-preserved family was buried near three other graves containing the skeletons of nine people in a Stone Age cemetery near Eulau in Germany. The mother was 35 to 50 years old and was laid to rest according to custom, on her left side, with her head pointing to the east. Her male partner, aged 40 to 60, was also in a traditional position.

The two boys, aged about four and eight, should also have lain like their father. But "it appears that the burial orientation pattern was overruled for each boy to face a parent to express a biological relationship", Dr Haak, whose study is published in the Proceedings Of The National Academy Of Sciences, said. The 13 people were all participants in a prehistoric tragedy. One woman had a stone arrowhead embedded in her spine. Others had fractured skulls, including the family's eight-year-old, and some had injuries on their arms and hands where they had tried to defend themselves from blows. This suggested they were victims of a sudden, fierce raid, the researchers said. "The injury patterns point to a violent event which most probably resulted in the death of all 13 individuals."

Survivors had obviously had an intimate knowledge of the victims' relationships from the careful way they had buried the slain. One of the graves contained a woman, two children and a baby. DNA testing showed the children were probably brother and sister, but the woman was not their mother. And this was reflected in the pair's burial position near her, but not facing her.

Studies of strontium in the people's teeth also revealed the women in the group had grown up elsewhere, while the men and children were from the local area. The men and boys were buried with stone axes and the women and girls with animal tooth pendants and flint tools.