Chicago ? Illinois opened a marathon series of clemency hearings Tuesday for nearly every prisoner on death row in what could be the most sweeping review of capital punishment in U.S. history.

In all, more than 140 petitions for clemency will be heard before the end of next week. The hearings for all but a few of the state’s 160 condemned inmates come after Gov. George Ryan said earlier this year that he intended to review every death penalty case before he leaves office in January.

“This is unprecedented,” said Robert Dunne, a member of the Illinois Prisoner Review Board. “Normally we only hear petitions for clemency from death row inmates when their executions are imminent.”

Ryan declared a moratorium on executions in 2000, calling the state’s death penalty system “fraught with error” after 13 inmates were found to have been wrongfully convicted.

The board will make confidential recommendations to the governor. But Ryan has suggested that he may grant a blanket clemency to all.

Prosecutors disputed the notion that the death penalty itself is on trial in Illinois. They argued that the clemency petitions must be considered by the board on a case-by-case basis.

“This is not a referendum on the death penalty,” David J. O’Connor, a Cook County prosecutor, told one of four panels of the review board.

From the beginning Tuesday, the battle lines were clear. Prosecutors highlighted evidence from scores of Illinois’ most notorious and gruesome murders, while defense lawyers pointed to weaknesses and apparent corruption in individual cases and in the criminal justice system as a whole.

In Chicago, prosecutors passed out yellow ribbons for the families of victims to make visible the dozens of relatives attending the hearings.

Board member Victor Brooks opened one of the first hearings with an apology to the victims’ families for forcing them to “revisit the unwarranted carnage inflicted on their lives.”

Richard Dean Pueschel sits next to a photo of himself with his mother and father, Dean and Jo Ellen Pueschel, during a clemency hearing in Chicago. The photo was taken not long before his parents were murdered and he was left for dead in 1983 by convicted killers Reginald and Jerry Mahaffey.

Emma Jean Burts left the hearing room in tears while listening to the case of Leonard Kidd, 48, who was convicted of setting a 1980 fire that killed 10 children, three of them hers. He was also convicted in the 1984 stabbing deaths of four people.

Prosecutors said Kidd has killed more children than anyone in the history of Illinois. But defense attorney Sharon Hicks argued Kidd is mentally retarded and was tortured by police to get him to confess.

At least 10 of the inmates seeking clemency contend their confessions were tortured out of them by Chicago detectives under the supervision of a police lieutenant who is no longer on the force. A judge has appointed a special prosecutor to examine those allegations.