LOS ANGELES — As Lance Armstrong continued to face fallout from doping allegations—this time, being stripped of his seven Tour de France titles—questions still surround a federal investigation that closed without criminal charges being filed.

U.S. Atty. Andre Birotte Jr.’s office declined to comment on the inquiry on Monday, other than to say the case remains closed. The cycling governing’s body announced Monday it would follow a U.S. Anti-Doping Agency recommendation that Armstrong be banned and lose the titles for being involved in the “most sophisticated, professionalized and successful doping program that sport has ever seen.”

In addition to the USADA inquiry, Armstrong — who has long denied doping allegations — was the focus of a separate two-year probe that was closed earlier this year. The grand jury investigation was confidential, but the media widely reported details about the former teammates and associates who were subpoenaed to testify about banned substances.

When announcing in February that no charges would be filed — a rare public statement on the closure of a secret probe — Birotte praised the work of investigators but gave no reason for concluding the investigation without charges.

Armstrong, however, said in a statement that it was the “right decision.”

When prosecutors first announced the investigation closed, USADA said its job was to “protect clean sport rather than enforce specific criminal laws.”

The USADA report released earlier this month said Armstrong and his teams used steroids, a blood booster and blood transfusions. Statements from 11 former teammates who testified against Armstrong were included.

A week after the report came out, Armstrong lost several major endorsements deals from companies including Nike and Anheuser-Busch.