For example, Nott, under a pseudonym, allegedly wrote to Pauley on Facebook, sending pictures and videos of skulls for sale. “These will be here soon,” Nott wrote, according to the FBI.

The Swan at Tetsworth, the UK-based antique centre that put the skull on auction, advertised it as part of their “Curious Collector Sale”, valued between £3,500 ($4,490) and £4,000 ($5,132).

An international group of 200 scientists and experts in looted art are protesting about the sale last month of a skull belonging to a member of the Fon people from Benin by Amsterdam auction house De ...