The U.S. government has demanded to see Lance Armstrong’s medical records from 1996 to see if his doctors knew he was using performance-enhancing drugs.

The subpoena to the Indiana University School of Medicine is for Armstrong’s medical records during the time he was treated for testicular cancer. It’s part of the evidence gathering phase of a lawsuit on the part of the federal government to be repaid millions of dollars in sponsorship money that the Postal Service paid to Armstrong’s team, AP reports.

Armstrong’s lawyers have said releasing the medical records would violate their client’s privacy. Armstrong admitted to doping in 2013 and has been stripped of his seven Tour de France titles.

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Write to Tessa Berenson at tessa.berenson@time.com.