American middle-distance runner Jonah Koech has been banned from the sport for three years for blood doping.
The US Anti-Doping Agency (USADA) said Koech's doping violation was identified after "highly atypical blood values in his athlete biological passport (ABP)".
An ABP tracks an athlete's blood values over time to identify signs of doping even without a positive drug test.
Koech had emerged as the surprise winner in men's 1500m at the US Outdoor Championships last year, finishing ahead of Ethan Strand and 2024 Olympic gold medallist Cole Hocker in a meet record three minutes 30.17 seconds.
His title has now been stripped after the 29-year-old accepted the ban "for the use of a prohibited substance and/or method", USADA said.
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Koech's blood samples were collected before and after the US Outdoor Championships on 30 July and 8 August last year.
He has not raced since finishing 13th in the 1500m final at the World Championships in Tokyo last September.
Born in Kenya, Koech competed collegiately in the United States from 2015 to 2019 before becoming eligible to represent the country in June 2021.
