Former U.S. Senator George Mitchell will release a long-awaited report on steroid use in Major League Baseball Thursday with as many as 50 current and former Major League players named as drug cheats.

Baseball Commissioner Bud Selig asked Mitchell to head an investigation into drug use by baseball players. A former federal prosecutor, Mitchell is expected to use documentary evidence - canceled checks, shipping slips and phone records, but not positive drug tests - to support his findings.

The report is expected to provide a tough critique of how baseball allowed steroids, human growth hormone, and amphetamines to become a part of the sport. Media reports have linked several All-Stars and MVPs to performance-enhancers in recent years, among them home run king Barry Bonds, Jose Canseco, Ken Caminiti, Juan Gonzalez and former home run record holder Mark McGwire.

Active players named in the report are expected to face less than the current penalty of a 50-game suspension for first-time steroid use. The discipline is expected to be based upon the rules in place when the players were implicated. Baseball did not have penalty testing for steroids until 2004.

The report will come less than one week after Bonds pleaded not guilty to obstruction of justice and perjury charges in connection with his testimony in the so-called BALCO doping case. Bonds has denied knowingly using drugs, and has never tested positive for steroids.

Some information for this report was provided by AP.