Clemens name surfaced in an investigation into the use of performance-enhancing substances in baseball by former U.S. Sen. George Mitchell, D-Maine.
"We are convinced the conclusions in Mitchell's report are wrong and are investigating the findings ourselves," Hardin told The New York Times in a telephone interview. "At this stage we have uncovered a lot of logical people who we thought Mitchell was going to talk to but never talked to him or his investigators. That's troubling."
The Mitchell report, released more than two weeks ago, quotes former trainer Brian McNamee as saying he gave Clemens steroids and human growth hormone during his 1998 stint with the Toronto Blue Jays and in 2000 and 2001 when Clemens was a Yankee.
Clemens is to discuss the issue on "60 Minutes" Jan. 6 and also planned to meet with reporters that day, Hardin said.