Left-hander Michael O'Connor, released by the Twins last month, was suspended 50 games on Tuesday after testing positive for a banned steroid.
The Office of the Commissioner of Baseball announced that O'Connor, who appeared in 13 games out of the bullpen for Triple-A Rochester this season, received a 50-game ban without pay after testing positive for metabolites of Trenbolone, a performance-enhancing substance, in violation of the Minor League Drug Prevention and Treatment Program.
The suspension will be effective once the 32-year-old southpaw signs with another Major League organization.
O'Connor, who spent parts of three seasons in the Majors, has pitched for six organizations during a 12-year career that began in 2002 after he was drafted in the seventh round by the Montreal Expos out of George Washington University.
He made his Major League debut in 2006 with the Nationals, throwing 105 innings over 21 outings, including 20 starts, before returning for six games in 2008. He also made nine appearances for the Mets in 2011.
In three big league seasons, O'Connor is 4-10 with a 5.30 ERA and 71 strikeouts in 120 2/3 innings.
O'Connor, 0-1 with a 4.86 ERA in 13 games this year, was released by the Twins on June 2 after signing a Minor League contract with the club on April 6. He became a free agent last December after going 3-6 with a 3.73 ERA in 31 games with Triple-A Scranton/Wilkes-Barre in the Yankees system.
Trenbolone, an illegal drug for human use in the United States, is a steroid used by veterinarians on livestock to increase muscle growth and appetite. It has similar effects on humans as it's been known to help burn fat and increase body mass among bodybuilders.
O'Connor is the 25th player to be suspended this year by Major League Baseball for violations of the Minor League drug program.