The report says the department tried to save money by releasing prisoners early but failed to take into account the possible impact on public safety.
MGT stands for "meritorious good time." It's the credit a prisoner is supposed to get for good behavior that can reduce a prison sentence by months or even years.
Just over a year ago, the Quinn administration took the idea another step and implemented a program called MGT Push, an accelerated early-release program that put hundreds of convicts, including some violence in their backgrounds, back on the street.
"MGT was a dismal failure. It was totally dysfunctional," said Judge David Erickson, Kent College of Law.
The law professor and former judge who led the investigation said that under the state prison system's MGT programs many convicts qualified without trying.
"Inmates did not have to do anything to earn their good time," said Erickson.
Judge Erickson concluded the Quinn administration's accelerated MGT Push program was implemented in September, 2009 by the cash-strapped state for the wrong reason.
"It had become a means by which the Department of Corrections was managing or controlling a prison population," said Erickson.
After news reports that violent offenders were being released, some after serving only a few days or weeks of their sentences, MGT Push became a political issue during the Democratic primary. Incumbent Pat Quinn blamed his director of corrections Michael Randle for including violent offenders in the program that the governor says was designed for non-violent convicts.
"It shouldn't have happened that way. It did. As director, I'm responsible," said Michael Randle, Illinois Department of Corrections.
Last year, Quinn ended MGT Push permanently and suspended other programs offering inmates meritorious good time.
" The MGT Push, the accelerated program, was flawed and it needed to be terminated. The governor terminated it," said Jerome Stermer, governor's chief of staff.
The governor's chief of staff also blamed the prison system's antiquated computer system for the early release of violent inmates who were not properly tracked.
Republican lawmakers say the MGT Push controversy illustrates how they say the Quinn administration's mismanagement of state government has risked the public safety.
"Their first and foremost responsibility is to do everything for public safety. This was an error of epic proportions," said Rep. Jim Durkin, (R) Western Springs.
The governor-- who spent Friday morning at the State Fair in Springfield-- held a news conference in Chicago during which he took responsibility for the flawed program. Since the governor ended or suspended the early release programs in Illinois, the prison population has increased by 2,500 or so inmates.