Stolen Stela Undetected Thirty Years on No-questions-asked Market

AT editor, 'Antiquities mystery solved: Swiss return stolen artifact to Egypt', Africa Times 14 November 2016

An ancient stela without any paperwork was discovered by Swiss authorities during a customs control in Geneva in 2014. Police opened a criminal case into the unknown object’s provenance.
It was turned over to Egyptologist Philippe Collombert at the University of Geneva, according to Agence France Presse. Collombert traced its origin to the ancient Isis temple in the Nile River delta. The engraved slab had been stolen from the temple at the Behbeit El Hagar archaeological site 30 years ago. The antiquities experts compared photographs taken in the 1970s to more recent ones, and established without a doubt that the object was from Behbeit El Hagar, according to a statement released to news agencies by the Geneva prosecutor’s office.

Now it remains to establish who had handled the stolen item in the past thirty years, how and where it entered the market, who then passed it on without checking it could be shown to have been of licit origins, a two-year investigation as part of a criminal case should have been enough to ascertain that, surely? because while the Egyptologist was sorting out from which site it had been stolen, what were the Swiss police doing?