Former Tokyo marathon winner Ruti Aga has been banned for six years for taking a banned substance and then trying to mislead investigators, the Athletics Integrity Unity (AIU) said on Thursday.
The 32-year-old Ethiopian won the Tokyo race in 2019 and finished in the top three in four World Marathon Majors.
An anti-doping test she took after a race in China in March this year showed traces of methylprednisolone, an anti-inflammatory medicine often used to treat severe asthma that is on the prohibited list.
The AIU said Aga then attempted to mislead investigators by providing false information in an interview and producing a forced document "that purported to verify a prescription for methylprednisolone while as an outpatient of a medical facility".
Aga attributed her positive test to treatment for a knee injury but the prescription she submitted was from a non-existent clinic and issued by a 'doctor' who turned out to be a family member with no medical registration.
Aga received a two-year ban for doping, with an added four years for tampering with evidence.
"We have made significant progress against doping in marathon running over the past six to seven years, but much remains to be done. Investigations are vital to uncovering doping and exposing false explanations. Protecting clean competition takes resources, but this case sends a clear message: attempts to cheat will be exposed," AIU chief executive Brett Clothier said in a statement.