Russian biathletes Ekaterina Iourieva and Irina Starykh could face extended suspensions after the International Biathlon Union (IBU) re-analysed samples that showed atypical results in previous seasons.
Iourieva was handed an eight-year ban for her second offence and Starkh two-years for a first failed test.
The IBU announced that after testing samples stored for potential future analysis, the World Anti-Doping Agency (WADA) found five samples positive for recombinant EPO.
Two of these re-analysed belonged to Starykh and one to Iourieva.
Neither athlete has requested their B-samples be tested.
Starykh's sample was collected in Oberhof, Germany, on January 2, 2014, and Iourieva's samples for re-analysis were collected in Östersund, Sweden, on November 28 and 29, 2013.
Due to the new findings the IBU Anti-Doping Hearing panel has "now to decide about the possibility of increasing the period of ineligibility for both athletes".
Upon failing her second doping test, Iourieva announced her retirement from the sport, seemingly in acceptance of a lengthy ban coming her way.
In the latest re-analysis, the IBU also announced the suspension of two further athletes, although no names were given.
The two suspensions came into effect on November 25 and December 15 for the two athletes.
In November the Russian Biathlon Union announced the suspension of Alexander Loginov after failed drugs results taken in November 2013.
The 20-year-old four-time World Junior Championship gold medallist and Sochi Olympian, was withdrawn from the opening World Cup competition in Östersund and will potentially lose a World Cup relay gold and have his Sochi results struck from the history books.
Loginov is believed to be the unnamed athlete detailed in the IBU release, although the athlete banned from December 15 is still unknown.
Biathlon was also rocked during the Olympics in February when two-time Olympic champion Evi Sachenbacher-Stehle of Germany was caught doping.
Her initial two-year ban was reduced to just six-months last month after the Court of Arbitration for Sport deemed that the athlete's adverse analytical finding was caused by contamination and that the athlete's degree of fault was minimal.
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November 2014: German biathlete's doping ban cut to six months after it's found she's not to blame
July 2014: Russian biathlete handed eight-year doping ban despite retiring in February
July 2014: First athlete to test positive at Sochi 2014 handed two-year ban
February 2014: Biathlete Iourieva retiring rather than face life ban after second positive test
January 2014: Starykh removed from Russian Olympic biathlon team after positive drugs test confirmed