Indian discus thrower Arjun, a youth Olympics silver medallist, tested positive for banned substances after his samples were tested in a foreign lab, reported The Indian Express. However, the kicker here is that the same samples had shown negative results for substance abuse when tested at the National Dope Testing Laboratory in New Delhi a year ago.

This could be the first case when an Indian sportsperson’s sample has tested positive in a foreign lab after it returned a negative result at home, according to the report.

Arjun’s doping violation case has been going on for more than a year. The samples were fist collected during the Indian Grand Prix in April last year, after which they were tested at NDTL. However, the initial negative report didn’t seem to satisfy the International Association of Athletics Federations as they requested them to be sent to the World Anti-Doping Agency-accredited laboratory in Cologne on June 22, 2016.

The test in Cologne turned out to be positive for androsterone and testosterone, putting both Arjun and NDTL in the dock. This case indicated that Wada and IAAF are monitoring the doping situation in India.

However, Arjun is still fighting to clear his name. According to the report, his lawyer Hemant Raj Phalpher has asked NDTL for the chain of custody of the sample from Delhi to Cologne. “NDTL has not provided vital documents [chain of custody] and it raises serious doubts on the credibility of the sample and whether it was handled and stored as per international standards of testing,” he was quoted as saying by Indian Express.

In the recent past, several Indian athletes have come under the doping scanner. Among the most high-profile cases are wrestler Narsingh Yadav, who had gone as far as Rio for the Olympics before his appeal was turned down and he received a four-year suspension, and Manpreet Kaur, who had won gold at the Asian Athletics Championships in Bhubaneswar in July.