By Federal Agents
If federal agents were looking for a smoking gun in the Lance Armstrong doping scandal ... they were hoping it might be Sheryl Crow -- this according to a new report.
The country-singer was called in by federal agents in late 2011 and questioned about any knowledge she might have regarding accusations that Armstrong was using illegal substances ... this according to The New York Daily News.
The move to question Crow makes sense ... she dated Armstrong from 2003 to 2006 (he won 2 Tour de France titles in that time span) -- and spent lots of time with him in Europe, traveling on private jets and in other locations where, according to the report, Armstrong allegedly participated in doping programs.
It's unclear what information Crow gave during her interview ... both the Feds and her attorney declined to comment.
As you know -- the U.S. Anti-Doping Agency recently stripped Armstrong of his 7 Tour de France Titles in late August and banned him from the sport of cycling ... after he dropped his case to fight back against doping allegations.