The three-time Boston Marathon champion became the most high-profile Kenyan athlete to fail a drugs test when she tested positive for banned blood booster erythropoietin (rEPO) in 2014.

She was handed a two-year suspension by Athletics Kenya, which had been due to expire this month.

An appeal was filed by the International Association of Athletics Federations (IAAF) calling for a longer suspension.

"In coming to its decision, the Panel found to its comfortable satisfaction that the athlete used rEPO over a period of time to enhance performance," the CAS panel chaired by Germany's Ulrich Haas concluded.

"The undisputed source of the rEPO found in her sample of September 25, 2014 was an injection given to her by a doctor. 

"The athlete provided various differing accounts of the circumstances leading up to the injection and also regarding her relationship with that doctor.

"According to the applicable rules, the minimum period of ineligibility in this situation is a sanction of two years but can be increased to up to four years in the case of aggravating circumstances."

Jeptoo had claimed she was prescribed banned substances at a local hospital after a road accident and had vowed to prove her innocence.

But she is now banned until October 30, 2018, while also being handed a fine of CHF15,000 (£12,400/$15,100/€13,800) in contributions to the IAAF's legal fees and expenses.

She also appears set to be stripped of the 2013-14 World Marathon Majors title in favour of compatriot Edna Kiplagat.

The CAS arbitrators claimed there were "aggravating circumstances" because "it was obvious to the Panel that the athlete used rEPO as part of a scheme or plan". 

"The evidence for this includes inter alia her long relationship with the doctor in question, her multiple visits to see him, that her rEPO use was consistent with her competition calendar, that she hid the visits to the doctor in question from her manager and coach, as well as her deceptive and obstructive conduct throughout the proceedings.

"Weighing all the evidence, the Panel is comfortably satisfied that the circumstances warrant a period of ineligibility of four years."

The case has, however, raised questions about how CAS deals with athletes implicated in doping cases.

A hearing scheduled to take place in April was postponed when Jeptoo’s first counsel withdrew shortly beforehand. 

Legal aid in the form of a pro bono lawyer from Nairobi was then provided to assist her for a case scheduled for July 7.

But lawyer Sarah Ochwada pulled-out two days before the hearing, citing "prejudice" against her client.

Jeptoo then joined the initial phase of the hearing via telephone before hanging-up during the opening statements.

She claimed afterwards that she had not done so deliberately and had called the court again, only to be replied to in French, a language she does not speak.

The 35-year-old had also hoped to return to competition but it is now thought likely that the CAS verdict will effectively end her career.

It is still possible she will appeal the decision, however.

“I have not spoken to her or seen anything but I was expecting that because she opted to test her B Sample where they messed something," her partner Noah Busienei told the Citizen Digital website today.

"They had said they would add two years and she was aware of that.

“There is no other avenue available to appeal the decision and we shall decide the way forward."