On 4 July 2012, Al Jazeera published the results of a nine-month investigation, which revealed that none of the causes of Arafat's death suggested in several rumors could be true. Tests carried out by a Swiss scientific experts found traces of polonium in quantities much higher than could occur naturally on Arafat's personal belongings. On 12 October 2013, the British medical journal "The Lancet" published a peer-reviewed article by the Swiss experts about the analysis of the 38 samples of Arafat's clothes and belongings and 37 reference samples which were known to be polonium-free, suggesting that Arafat could have died of polonium poisoning.