The Kenyan runner exceeded Ethiopian Tigst Assefa's female marathon global best by nearly 120 seconds at the marathon event in Chicago in the year 2024.
Female long-distance global champion the athlete has been prohibited for three years after the Kenyan acknowledged doping rule violations.
The record holder was temporarily banned in July following a positive test for Hydrochlorothiazide (HCTZ) - a prohibited substance used commonly as a concealing drug - on March 14.
Chepngetich's accomplishments which occurred before that test - such as her global best performance of 2:09:56 in Chicago in 2024 - will still stand.
The sports governing body had requested a 48-month suspension but the runner's punishment was lowered to three years because she confessed to the violations.
Nonetheless, the AIU will continue to investigate evidence from the athlete's phone which it found suggest "strong grounds that her positive test may have been deliberate" - featuring messages dating back to 2022.
"This matter regarding the positive test for HCTZ has been settled, but the AIU will keep looking into the questionable evidence recovered from Chepngetich's device to determine if any other violations have taken place."
When interviewed in April by the integrity body, Chepngetich, the initial female to run a marathon in under 2:10, could not provide an explanation for the positive test.
While the substance has a lowest detectable limit of 20 nanograms per millilitre (ng/mL) in urine, the athlete's sample showed an estimated concentration of 3,800 ng/mL.
Traces of HCTZ below the detection threshold were also found in a test taken from the runner two weeks earlier, on February 28.
At a later interview on 11 July, the record holder was presented with the previously mentioned questionable proof obtained from her mobile. Meanwhile, accidental exposure had also been disproven by the AIU.
Chepngetich altered her story on July 31, claiming that she had used her domestic worker's medication - labeled as being the banned substance - after becoming ill 48 hours prior to the failed test.
The AIU had "serious reservations about the credibility of the revised account" and, in the context of the athletics' doping rules, such "recklessness" is deemed "implied intention, for which an increased four-year sanction is applicable".
An automatic one-year reduction was applied after the runner confessed to the doping rule violations within the specified 20-day period.
The 36-month suspension commenced on 19 April - when the athlete agreed to a temporary ban - with the competitor's results, honors, championships, appearance and earnings since 14 March forfeited.
"Nobody is above the rules."
"Although unfortunate for those who put their trust in this athlete, this is how the process is designed to operate."
"The road-running industry should be commended for collectively funding anti-doping efforts able to uncovering doping violations performed by top competitors in their events."
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