According to a report published on the New York Times Web site Tuesday, adding credibility to those who've questioned his power surge for years, Sosa benefited from banned substances, not Bam Bam supplements.
Sosa allegedly is among the 104 Major League players who tested positive for performance-enhancing drugs in 2003.
The allegation of the test came from what the Times referred to as "lawyers with knowledge of the drug-testing results from that year." Alex Rodriguez is the only other player whose name has been linked to the positive results in 2003.
"It's unfortunate that things that were supposed to be confidential weren't," Cubs outfielder Milton Bradley said of the 2003 tests. "Here's a guy who people admired and looked up to, and now he's got to deal with it. Anyway you look at it, it's not good."
The 2003 test was the first such test conducted by Major League Baseball. Under guidelines agreed upon with the players union, the test results were to remain anonymous but would lead to testing with penalties the next year if more than 5 percent of the results were positive.
The lawyers who allegedly had knowledge of Sosa's inclusion on the 2003 list did not know the substance for which Sosa tested positive. They spoke on condition of anonymity, because they did not want to be identified as discussing material that is sealed by a court order.
"We all assume there was an era when a lot of people took things that would now be illegal, but the rules weren't set up stringent enough to enforce it at the time," Cubs general manager Jim Hendry said Tuesday.
"I think you have to judge people for the era they were in," Hendry said. "Unless all the facts are in, speculation is a waste of time. You'll never be able to go back and figure out who did what for sure. I'm not condoning it at all. As long as there is competitive athletics and people can get away with things, they'll try to get a competitive edge."
Sosa began his career in 1989 with the Rangers, who traded him to the White Sox during that season. He played for the Cubs from 1992-2004, and is the team's all-time home run leader with 545. He played one season in Baltimore in '05 and one in Texas in '07, finishing his 18-year career with 609 home runs.
"It's a shame that baseball keeps going back to the past," Cubs manager Lou Piniella said. "Baseball is doing a good job today of cleaning up all these issues. That's what we should be focusing on. I don't know how this news gets out. In my case, I wasn't here, and I wish that we would just focus on today and what the sport is doing as opposed to what happened in the past."
Both Piniella and White Sox manager Ozzie Guillen said they would prefer to see the entire list made public.
"It would probably create a lot of havoc, but I think it would be the best thing," Piniella said.
"It's very, very, very sad how names start to come out," Guillen said. "And every week baseball has to deal with these names. And whoever is leaking the information, whoever got the rights to the information, they should right away say something and get it over with, because it's put everyone in baseball, not just Chicago people, everyone in baseball, dealing with this situation they shouldn't be dealing with any more. We got enough time to clean this thing."
Guillen said it's not fair to the game to be revealing names in such a random fashion.
"It's not good for us to answer people's questions when we don't have anything to do with this," Guillen said. "That's an uncomfortable situation, because you want to protect the guys but you have to get interviewed about the game and I'm about protecting the baseball game. And I think the best thing we can do is get those names out there, deal with it and be done with it."
When Piniella played in the 1970s and early '80s, he said steroids weren't a topic.
"In the era that I played, it wasn't a problem," Piniella said. "I don't know that much about it. Maybe if managers had been trained a little more in these areas, I could answer better, but I don't know. I wouldn't know a steroid from a reefer."
Sosa and Mark McGwire were credited with bringing fans back to baseball after the 1994 strike, when in '98 they chased Maris' single-season home run record of 61. McGwire hit 70 that year for the St. Louis Cardinals, and Sosa belted 66 for the Cubs, the first of three 60-homer seasons by the right fielder. Sosa's best season prior to '98 was '96, when he hit 40. He hit 36 home runs in '97.
Sosa has not played in the Major Leagues since 2007. At a Congressional hearing in '05, he testified under oath that he had never taken illegal performance-enhancing drugs.
Hendry joined the Cubs in 1994 as director of player development and was named general manager in July 2002. He said he never asked Sosa about whether he used steroids. Did he suspect anything?
"If you were in baseball at any time, you sometimes left the ballpark thinking, 'That guy has a lot more power than he used to,' or 'That guy is a lot bigger than he used to be,'" Hendry said. "You didn't think a guy was necessarily going into the back room and doing something before the game.
"From a general manager's point of view, it became a tough job to decide contract-wise or free-agent-wise or long-term-wise, because you never know. That's why I applaud stricter rules."
The news about Sosa came just as two of his former teams, the Cubs and White Sox, were set to begin a three-game Interleague series. It shocked both clubhouses.
"Sammy is one of our leaders," White Sox pitcher Octavio Dotel said. "Not only that, Sammy Sosa is everywhere. Like in Latin America, he's one of the big baseball players.
"That's a tough one. If that's true, I mean, it's hard to understand, but at this point, I'll believe anything, because I see things that I never thought, that this guy is going to be doing this, this guy is going to be doing that. At this point, nothing surprises me."
Would this tarnish Sosa's image?
"It's kind of hard now to understand that he went through this situation," Dotel said. "It's really, really, really tough, because it also takes from him his Hall of Fame thing. It's kind of hard to know, and just to hear this about if he did it or not, it's really, really tough, especially for me personally.
"Hey, Sammy is one of our leaders in the Dominican Republic. He's one of the guys who did unbelievable things in baseball. It's a big mistake. He didn't kill nobody, yes. But it's a big mistake by him."
The news surprised Cubs outfielder Alfonso Soriano.
"To me, things about steroids, I don't like to talk about it," Soriano said. "I never used it, I don't know what it is."
Hendry would like to see baseball move on.
"It's time to put that whole era behind us," he said. "All the people who might have dabbled in it will never get caught. I feel bad for the thousands of guys who played the game right and are lumped into an era of cheating."
Ranked sixth on Major League Baseball's career home run list, Sosa said in a recent interview with ESPN Deportes that he would "calmly wait" for his induction into the Hall of Fame. He'll be eligible in 2013.
Is Sosa still a hero in the Dominican Republic?
"He is," Soriano said. "He put up some good numbers and everybody in the Dominican and all over the world followed him and McGwire.
"He used to be my hero because I watched him a lot playing baseball when I was growing up. He knows what he did. He's still my hero, no matter what."
Carrie Muskat is a reporter for MLB.com. Scott Merkin and Jesse Noble contributed to this story. This story was not subject to the approval of Major League Baseball or its clubs.