Ruth Chepngetich broke Ethiopian Tigst Assefa's female marathon global best by almost two minutes at the marathon event in Chicago in 2024.
Female long-distance global champion the athlete has been prohibited for 36 months after the runner admitted to anti-doping infractions.
The record holder was temporarily banned in the seventh month following a positive test for a banned substance - a prohibited substance often utilized as a masking agent - on 14 March.
The athlete's achievements which pre-date that sample - such as her world record time of two hours, nine minutes and 56 seconds in Chicago in October 2024 - will remain valid.
The Athletics Integrity Unit (AIU) had requested a 48-month suspension but the 31-year-old penalty was reduced to 36 months because she confessed to the infractions.
Nonetheless, the AIU will continue to investigate proof from Chepngetich's mobile device which it found suggest "strong grounds that her positive test may have been deliberate" - including messages from as early as 2022.
"The case concerning the failed test for the substance has been settled, but the AIU will continue to investigate the suspicious material found on the runner's device to ascertain if any further infractions have taken place."
When interviewed in April by the integrity body, Chepngetich, the first woman to complete a marathon in under 2:10, could not provide an explanation for the failed test.
While HCTZ has a minimum reporting level of 20 nanograms per millilitre (ng/mL) in urine, Chepngetich's sample showed an approximate level of 3,800 ng/mL.
Small amounts of the diuretic under the detection threshold were also found in a test collected from the runner two weeks earlier, on February 28.
At a subsequent meeting on July 11, Chepngetich was shown the aforementioned questionable proof obtained from her phone. Meanwhile, accidental exposure had also been disproven by the AIU.
The athlete changed her explanation on July 31, claiming that she had used her housemaid's medication - marked as being the banned substance - after falling sick two days before the failed test.
The AIU had "serious reservations about the reliability of the new version of events" and, in the framework of the sport's anti-doping rules, such "carelessness" is considered "implied intention, for which an increased four-year penalty is applicable".
An standard 12-month decrease was applied after the runner admitted the doping rule violations within the specified 20-day period.
The three-year ban commenced on April 19 - when Chepngetich accepted a temporary ban - with the runner's results, honors, titles, appearance and earnings from March 14 forfeited.
"Nobody is exempt from regulations."
"While disappointing for those who had faith in this runner, this is how the process is designed to operate."
"Marathon organizers should be commended for jointly supporting anti-doping efforts capable of uncovering substance abuses committed by elite athletes in their races."