Three-time world champion and Beijing 2008 Olympic 1,500 metres gold medallist Asbel Kiprop has been given a four-year ban after he tested positive for a banned substance.
A sample provided by Kiprop, the third-fastest 1,500m runner of all time, in an out-of-competition test in November 2017 was found to have contained erythropoietin, also known as EPO.
The 29-year-old consistently pleaded his innocence and made several claims in an attempt to explain the failed test, including that his sample had been tampered with.
But the Athletics Integrity Unit (AIU) panel said the case against Kiprop had been "convincingly made out", although it again admitted the athlete had been given advance notice of the planned test.
The decision rules Kiprop out of next year's Olympic Games in Tokyo, while his results from November 2017 to February 2018 have been disqualified.
Kiprop has the right of appeal to the Court of Arbitration for Sport.
"The panel is aware that its order will interrupt and even terminate the athlete's sporting career and cast a shadow over his impressive competitive record," the panel said in a statement.
"But in its opinion, the laboratory results viewed in the context of the evidential record and the regulatory framework admit of no other conclusion than that the case against the athlete is convincingly made out."
Kiprop, who claimed he had been asked for money from the doping control officer, gave six possible reasons for the failed test.
He argued the EPO found in his sample was natural as he had been training at altitude and claimed medication he was taking at the time may have contained traces of the blood booster.
Kiprop, who won the 1,500m event at three consecutive World Championships from 2011 to 2015, also said the sample collection procedures were "not conducted properly" and that he was the victim of "spiking or substitution".
The Kenyan claimed the chain of custody of his sample may have been broken or that analytical procedures were incorrect.
The panel rejected the explanations from Kiprop, who also hoped his previous record and his "antipathy to doping" – he initially finished second in the 1,500m at Beijing 2008 but was upgraded to gold when Bahrain's Rashid Ramzi failed a drugs test – would count in his favour.
It also confirmed Kiprop had given the anti-doping official money but found no link between that and the positive test.
Kiprop becomes the latest Kenyan to be banned for an anti-doping violation amid a swathe of doping offences involving competitors from the African nation.