On 6 November 2013, Al Jazeera reported that the Swiss forensic team had found levels of polonium in Arafat's ribs and pelvis 18 to 36 times the average. According to the Swiss expert team (including notably experts in radio-chemistry, radio-physics and legal medicine), on a probability scale ranging from one to six, death by polonium poisoning is around five. While Al Jazeera reported that the scientist were "confident up to an 83 percent level" that polonium poisoning occurred, but Francois Bochud (the head of the Swiss team) clarified to Al Jazeera that this is not the case and that the scale does not allow a simple division like this; he stated only that the poisoning hypothesis by polonium is "reasonably supported". Forensic Biologist Nathan Lents of the John Jay College of Criminal Justice, said the report's results are consistent with a possible polonium poisoning, but "There's certainly not a smoking gun here." Derek Hill, a professor in radiological science at University College London who was not involved in the investigation, said "I would say it's clearly not overwhelming proof, and there is a risk of contamination (of the samples), but it is a pretty strong signal. ... It seems likely what they're doing is putting a very cautious interpretation of strong data."