The interview with Mitchell lasted 45 minutes, with Thomas answering questions primarily about himself. It was a relatively insignificant session, but it became a key item within the 311 pages of the Mitchell Report, which was made public in December.
Every one of the players named in the Report -- and a handful like Thomas, who weren't facing allegations -- were asked to take part in interviews. What the 39-year-old Thomas might not have realized at the time was that he was the lone player who voluntarily agreed to meet with Mitchell to discuss drug use in baseball.
On Monday, Thomas spoke passionately about the matter, expressing dismay over the fact that no other players took part in the investigation. Toronto's designated hitter said he believes that the Players' Association may have pressured players not to speak, and that only fuels his disappointment in the fallout.
"I was shocked. I was really shocked," Thomas said emphatically. "But I think the Players' Association had a lot to do with that. For me, I've always been my own man. No one's going to tell me not to talk to anyone, especially when I've got nothing to hide."
Thomas said Mitchell stuck to questions about the veteran's knowledge of steroid use over the past decade and the former Senator didn't press for details. Thomas, who ranks 18th on the all-time list with 513 home runs, has been adamant about his clean reputation -- that he never used any illegal substances during the course of his 18 years in the game.
"He just asked, 'Did I ever see anything or hear anything,'" Thomas said. "I was like, 'No.' So I was definitely one of the naive guys of that era -- not knowing so many guys were involved. I'm really, really shocked, because I played with a few of those guys and had no clue.
"It's obvious now that there were a lot of guys involved with steroids and HGH. I'm shocked, because I played in that era and had to compete against it. But I'm shocked there were so many guys involved."
Throughout the Mitchell Report, the former Senator made sure to clearly state that he put in requests to speak with each player who was named, and that each subsequently declined. Early in the Report, Mitchell also noted that he asked five current Major Leaguers who had spoken publicly about the issue.
Mitchell wrote that he "made clear that there was no suggestion that any of the five had used performance enhancing substances." Four of the five players declined to meet with Mitchell, with the lone exception being Thomas. It's Thomas' belief that more players might've agreed to interviews under different circumstances.
"There were a lot of guys who wanted to speak out," Thomas said. "I'm glad I did speak out, because if I didn't I would've been on that list of 'Wouldn't talk to George Mitchell.' That would've put a stain on my career and I'm not going to let anyone stain my career."
Thomas wasn't concerned that they might be a negative reaction from players concerning his willingness to speak. He didn't provide any names to Mitchell and his participation was only to maintain his clean track record. Thomas said it was a shame that he was the only player to go forward.
"Backlash? Backlash for what? There's no backlash," Thomas said. "A congressman called me and asked me a question. What the [heck] am I going to run for? I had nothing to hide. There's no backlash. I think no one should've been hiding. Nothing needs to be hidden, because that stuff is illegal.
"To me, it's just one of those things where I'm more disappointed with the Players' Association, because I know the way they didn't want guys participating. I feel that this is over with now and we've got to move forward."
Within his own clubhouse, Thomas has a teammate who was implicated in the Report in catcher Gregg Zaun. Toronto's catcher has denied the accusations against him and Thomas said Zaun's involvement won't affect their relationship.
"There's nothing wrong with Zaunie," Thomas said. "Zaunie's a hard worker. He's not alone. If he's one of those guys, he's not alone. Come on, the list is out. That's part of it. A lot of people are saying it's probably double the names, so we'll see what happens. But who cares? It's time to move forward."
Thomas also said he paid close attention to the Congressional hearings on Capitol Hill last week, when pitcher Roger Clemens -- one of the more prominent players named in the Report -- testified under oath. Thomas said he was disappointed to see someone of Clemens' stature put under the microscope.
Thomas also said he believes airing the hearings on TV in front of a national audience was unnecessary. Given the seriousness of the allegations involved with the Mitchell Report, it's Thomas' opinion that the interviews should be held in a more private setting.
"I've had a lot of respect for him for many, many years," said Thomas, referring to Clemens. "I'm just amazed how many guys were doing these things. I feel bad for him, because I don't think it's something that should be handled on the national stage like that. I think it should be handled behind closed doors."
Thomas is quick to defend himself against the so-called Steroid Era. He stressed that the impressive statistics he's piled up over the years have come without the aid of performance enhancers. That doesn't mean Thomas doesn't understand why others might have been tempted to take a different route.
"The money went crazy in that era and people don't understand that," he said. "I think guys got to the point where, hey, they did some things they really didn't want to do. But with the money they were throwing out there, why not catch some of it?
"I think that was what a lot of them we're thinking. But when you're caught, it's a different situation. Now you've got to answer these things and it's kind of embarrassing for a lot of these guys. It's really embarrassing."
Jordan Bastian is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.