The Kenyan runner surpassed Ethiopian record holder's women's marathon global best by about 120 seconds at the Chicago Marathon in 2024.
Female long-distance world record-holder the athlete has been banned for three years after the runner confessed to doping infractions.
The record holder was provisionally suspended in July following a failed test for Hydrochlorothiazide (HCTZ) - a banned diuretic used commonly as a masking agent - on March 14.
Chepngetich's achievements which occurred before that test - including her world record performance of two hours, nine minutes and 56 seconds in the Chicago event in 2024 - will remain valid.
The sports governing body had sought a four-year ban but the 31-year-old penalty was reduced to 36 months because she admitted to the infractions.
Nonetheless, the integrity unit will continue to investigate proof from Chepngetich's mobile device which it found suggest "a reasonable suspicion that her failed test may have been deliberate" - including communications from as early as the year 2022.
"The case concerning the positive test for the substance has been resolved, but the unit will continue to investigate the suspicious material recovered from the runner's device to ascertain if any further infractions have occurred."
When interviewed in the fourth month by the AIU, the marathoner, the initial female to complete a marathon in less than 2 hours 10 minutes, was unable to give an explanation for the positive test.
Although HCTZ has a lowest detectable limit of 20 nanograms per millilitre (ng/mL) in samples, Chepngetich's test showed an approximate level of 3,800 ng/mL.
Traces of HCTZ below the minimal reporting level were also identified in a test collected from Chepngetich 14 days prior, on February 28.
At a later interview on July 11, the record holder was presented with the previously mentioned suspicious evidence acquired from her phone. Meanwhile, contamination had also been disproven by the authority.
The athlete altered her story on 31 July, claiming that she had used her domestic worker's pills - labeled as being HCTZ - after becoming ill 48 hours prior to the positive test.
The AIU had "major doubts about the reliability of the new version of events" and, in the framework of the sport's doping regulations, such "carelessness" is deemed "indirect intent, for which an increased four-year penalty is applicable".
An automatic one-year reduction was granted after the runner admitted the anti-doping breaches within the 20 days required.
The 36-month suspension started on April 19 - when Chepngetich agreed to a voluntary provisional suspension - with the runner's performances, awards, titles, appearance and earnings from March 14 forfeited.
"No one is exempt from regulations."
"Although disappointing for those who put their trust in this runner, this is how the system is supposed to work."
"The road-running industry should be commended for collectively funding doping prevention capable of uncovering doping violations committed by top competitors in their events."
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