MONACO -- Former London Marathon winner Daniel Wanjiru of Kenya has been banned from competition for four years for doping.
The Athletics Integrity Unit said it was "highly likely" that Wanjiru used prohibited substances, citing abnormalities in his biological passport.
The 28-year-old Wanjiru's four-year ban ends Dec. 8, 2023.
Wanjiru, who had been provisionally suspended in April, won the London Marathon in 2017 and the Amsterdam Marathon in 2016.
A blood test from March 9, 2019, showed an "extraordinarily high" hemoglobin level, the AIU said.
"We therefore confirm our previous opinion that it is highly unlikely that this profile is the result of a normal physiological or pathological condition, and it is highly likely that it was caused by the use of prohibited methods, with or without the use of prohibited substances," the AIU said in its findings.
Wanjiru's results from the date of his blood test are disqualified.
In April, Wanjiru proclaimed his innocence, arguing that the biological passport is "confusing and frustrating."
"We are very disappointed about this decision," Volare Sports, his Netherlands-based management agency, said in a statement Thursday. "We emphasize that no prohibited substance has ever been found and we strongly believe that Daniel is innocent."
Wanjiru has not returned a positive test, but an athlete's blood passport can reveal the effects of doping by interpreting sample results taken over an extended period.
He has until early November to appeal.
Wanjiru won the 2016 Amsterdam Marathon in 2 hours, 5 minutes, 21 seconds, a course record that has since been topped.