More than 5,500 years ago, two women were tied up and probably buried alive in a ritual sacrifice, using a form of torture associated today with the Italian Mafia, according to an analysis of skeletons discovered at an archaeological site in southwest France.

Researchers investigated the unusual position of three female skeletons found in 1985 at the site in the town of Saint-Paul-Trois-Châteaux, and concluded that two of the women probably died from a form of torture known as “incaprettamento,” which involves tying a person’s throat and ankles so that they eventually strangle themselves due to the position of their legs.

The researchers also reviewed skeletons found at other archaeological sites across Europe and identified 20 other probable instances of similar sacrificial killings. The practice may have been relatively widespread in Neolithic, or late Stone Age, Europe, according to the study, published in the journal Science Advances last week.

The women’s burial place was aligned with the sunrise at summer solstice and sunset at winter solstice, leading the study’s authors to hypothesize that this site acted as somewhere people gathered to mark the turning of the seasons, which may have involved human sacrifices.

“There is always this idea that somebody is dying and that the crops will grow,” Crubézy added, referencing that belief appearing in other cultures such as the Inca practice of human sacrifice in South America.

Crubézy was part of the original team that excavated the site in 1985 but it wasn’t until the break caused by the Covid-19 pandemic that he and his colleagues set about researching other instances of such sacrifices.

By reviewing the existing literature, researchers pinpointed 20 other probable examples of people being sacrificed in the same way over 2,000 years in the Neolithic period. The study said the actual number was probably higher but there was insufficient information about skeletons at other archaeological sites to draw firm conclusions.

“In different parts of Europe, it was the same type of sacrifice,” Crubezy said. “And this sacrifice is very particular because it’s a cruel one … and you have no blood and no people who killed another, the people killed themselves.”

Though it is impossible to prove definitively that the women in the grave at Saint-Paul-Trois-Châteaux died in situ, their position “stacked atop each other and entwined with fragments of grindstones” implies that they were placed there forcefully and deliberately, “strongly suggesting that their demise likely occurred” in the grave, the study said.

At the other sites across Europe, men and children as well as women were also found sacrificed in this way, the study said.

In the future, Crubézy says, the researchers intend to analyze the familial relationship between the three women at Saint-Paul-Trois-Châteaux and investigate unusual death rites observed in other graves around the site.