The Kenyan was tested in late September before defending her Chicago Marathon title. 

According to the website RunBlogRun, Kenyan Rita Jeptoo, winner of the last two Boston and Chicago marathons, tested positive for a banned substance in an out-of-competition test in late September, just weeks before winning for the second straight year in the Windy City.

Jeptoo, who failed her “A” test, has yet to have her “B” sample tested. Jeptoo, or one of her representatives, may be present when the B sample is tested. Should Jeptoo fail the “B” test, she will likely be stripped of her most recent marathon titles and face suspension from competition. 

The 2013-2014 World Marathon Majors awards ceremony was set to take place in New York this weekend but due to the circumstances, the organization has decided to postpone the event. Jeptoo was set to be awarded with the $500,000 first prize for winning the yearlong series.

“World Marathon Majors is disappointed to learn that Rita Jeptoo has apparently had an A test that proved positive for a banned substance under IAAF rules,” the World Marathon Majors said in a statement. “World Marathon Majors has been at the forefront of the fight against doping in our sport and has a rule that no athlete can win the World Marathon Majors Series title, who has been in breach of IAAF anti-doping rules. WMM events were the first major events to confirm that all elite athletes taking part in their events would be blood tested and have consistently called for wider testing by others. Additionally, WWM has previously agreed that any athlete found guilty of a doping offense will not be invited back to its races. As part of that fight against doping, WMM has been giving support and financial help to the IAAF anti doping drive and helped fund a wider programme of out of competition testing…At present there has been no decision in this case by the IAAF, including in relation to sanctions, and as a result WMM is unable to comment further until that determination has been made although in the circumstances it has been decided to postpone the WMM Awards Ceremony that was due to take place on November 2, 2014.”

In October, Jeptoo successfully defended her Chicago Marathon title, winning in 2:24:35. Earlier this year, she won her third Boston Marathon, clocking 2:18:57—a personal best and a course record by 1 minute and 46 seconds.

Jeptoo’s agent, Federico Rosa, was unavailable for comment at the time of the report and Athletics Kenya president Isaiah Kiplagat told, “We will only speak about the matter when we receive notification from IAAF or WADA. I have seen the online report but we do not want to pre-empt anything since of the seriousness of the matter.”