Findings: Mummy lied about her age

It was supposed to be the archaeological find of the century - the gilded mummy of a Persian princess. Yet when the first carbon-dating results emerged from the coffin, Wolfgang Kretschmer knew immediately that something was very wrong, writes Steve Farrar.

The professor of physics at Erlangen University subsequently found that the mummified body inside the ornate double sarcophagi was not Ruduuna, daughter of King Xerxes, as the coffin inscription proclaimed. The woman had died in 1995, not 2,500 years ago.

The Persian mummy's true provenance was revealed last September. Professor Kretschmer has now formally announced the results of his analysis at the fourth C14 and archaeology symposium at Oxford University.

Pakistani police recovered the remains from a house near the Iranian border in October 2000. They were told the mummy was expected to fetch millions of dollars on the black market. If genuine, the discovery would have had significant implications for archaeology.

Professor Kretschmer and his team were sent straw matting and linen from the coffin.

Using accelerator mass spectrometry, his team needed only milligrams of material to measure the tiny ratio of carbon 14 to carbon 12. This ratio stays steady in living organisms, but it declines slowly and constantly after death.

Professor Kretschmer's technique is more sensitive than conventional carbon dating, measuring carbon atoms directly as they are ionised, accelerated and separated through magnetic and electrical fields.

This test showed the mummy was at most 45 years old. The scientists then analysed samples of bone, skin and muscle tissue. As the carbon cycle in these materials is subtly different, Professor Kretschmer was able to get more precise results and to confirm that the woman had died in 1995.

The analysis matched other clues that the mummy was a fake, including the discovery of errors in the cuneiform inscription and pencil marks on the coffin.