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 by the end of the month. 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."

"It is better that maybe 10 people who deserve death don't get it to avoid executing one person who is innocent," Northwestern University law professor Lawrence Marshall argued on behalf of brothers Reginald and Jerry Mahaffey.

The two were convicted of beating Dean and Jo Ellen Pueschel to death with baseball bats in their Chicago home in 1983. The victims' son, Ricky, who was 11 years old at the time, was beaten and stabbed but survived.

"I am Richard Dean Pueschel. I am that little boy Ricky," the son said. "Let Governor Ryan know that Jerry and Reginald Mahaffey are guilty. I saw them killing my parents. I saw them. ... Let Governor Ryan know Reginald Mahaffey and Jerry Mahaffey do not deserve mercy."

Defense lawyers argued the brothers deserved clemency because they are mentally retarded and confessed only after they were tortured by police.

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.

In the case of Ronald Kitchen, who confessed to killing five people, his lawyer argued that he admitted to the crimes after being beaten in the groin with a nightstick.

"No one hit him, no one beat him, no one tortured him," countered Cook County prosecutor Steve Goebel.

"This man is an evil devil," said Rebecca Ramos, whose daughter was among those Kitchen was convicted of killing. "For the victims, I beg of you, please leave Ronald Kitchen to die."