A lawyer for Sosa, Jay Reisinger, declined comment to the Times. An MLB official likewise declined comment to the newspaper.
"There was always that question mark about 'Did he or didn't he?' and if this report is right, now we know he did," Cubs legend and Hall of Famer Fergie Jenkins told ESPN. "I always thought he was clean and got bigger just with his hard work."
Jenkins added: "I coached Sammy when he was a kid in the '90s and he became a 30-30 [homers and stolen bases] guy. As guys progressed, I guess he was on the bandwagon and used -- they did and so did he. Now it's coming out, who did what, when and where."
The lawyers who have knowledge of the 2003 list results do not know the substance that caused Sosa to test positive, according to the Times. Results from the 2003 surveys were supposed to remain anonymous. But on Feb. 7, Sports Illustrated reported that Yankees third baseman Alex Rodriguez was one of the 104 who tested positive for performance-enhancing drugs.
Two days later, Rodriguez admitted to having taken steroids while with the Texas Rangers from 2001 to 2003.
Test samples and records were supposed to be destroyed, but union head Donald Fehr said the players' association didn't have enough time to make arrangements after the results became final Nov. 13, 2003.
The 9th U.S. Circuit Court of Appeals is considering the fate of the list and test specimens, which were seized by federal agents in April 2004.
ESPNdeportes.com reported in early June that Sosa, 40, was planning on announcing his formal retirement from baseball soon, and would not address allegations of steroid use.
"I will calmly wait for my induction to the Baseball Hall of Fame. Don't I have the numbers to be inducted?" said Sosa, who presently serves the Dominican government as special ambassador for investment opportunities.
Jenkins thinks otherwise.
"I don't think they [proven users of performance-enhancing drugs] belong in the Hall of Fame," Jenkins said. "The drugs probably enhanced their performances about 20-30 percent. Sammy was in his 30s when he was apparently using and it gave him an edge in homers and RBIs."
Sosa had a total of 609 home runs in his career, including seasons of 66 homers in 1998; 63 in 1999; and 64 in 2001.
He last played in 2007, when he was with the Rangers, a season he called his most fulfilling, with 21 home runs and 92 RBIs in only 114 games.
"I always played with love and responsibility and I assure you that I will not answer nor listen to rumors. If anything ugly comes up in the future, we will confront it immediately, but with all our strength because I will not allow anybody to tarnish what I did in the field," Sosa told ESPNdeportes.com.
Known as the "Caribbean Bambino" after he and Mark McGwire were locked in a home-run race in 1998 -- both ended up breaking Roger Maris' single-season record of 61 -- Sosa expressed sadness for the many Dominican players who are facing difficult moments in their careers, singling out Dodgers outfielder Manny Ramirez, who is serving a 50-game suspension for violating baseball's drug policy.