The man took two steps away from the vehicle, drew a gun and shot him dead.

Within five months, a local 21-year-old, Stanley Howard, was arrested and heading for death row.

Eighteen years later, Howard is still awaiting execution for the shooting, and his family still lives four blocks from where it happened, on a neatly manicured crossroads in a landscape still otherwise synonymous with African-American poverty and urban blight.

Almost everything else has changed. A federal judge has backed Howard's claim that he confessed only after having his breathing stifled with a typewriter dustcover, being handcuffed to a wall, and suffering a beating. The police commander in charge has left the force under a cloud of related torture charges. Compelling new evidence suggests that Ridgell's killer was actually an acquaintance.

And today or tomorrow, Howard will learn whether he is to escape death - and perhaps be freed altogether - when the governor of Illinois, George Ryan, announces his decision on whether to commute or overturn the sentences of some or all of the 160 prisoners on the state's death row.

Police torture

Mr Ryan suspended executions in Illinois three years ago, after the number of inmates found to have been wrongly sentenced to death reached 13 in 23 years.

His personal review of every case - which he must complete before leaving office on Monday - marks a moment without precedent in the history of the US, where the death penalty has long been untouchable in political debate.

It also testifies to the extraordinary personal journey of Mr Ryan, a patrician Republican, formerly a zealous advocate of lethal injection, who now finds himself doubting whether the state should ever assume the responsibility of taking a life.

"The governor is in the position of Jesus Christ, to a degree," says Perry Cobb, one of the exonerated death row inmates whose release inspired Mr Ryan's original moratorium, in turn prompting 15 more states to re-examine their laws.

"I say to him, don't you allow yourself to get blood on your hands from the people who have taken the hand of the devil."

The extraordinary power that Mr Ryan will wield, in two speeches scheduled for today and tomorrow, tends to inspire the language of religion.

"I have faith that the governor will do the right thing," says Tiffany Johnson, Howard's sister, as she waits pensively in her South Side home, blinds drawn against the sharp winter light. "But I can wait another two days. I've been patient 18 years - I can't do nothing but be patient now."

Howard's is only the most obviously shaky of a slew of convictions tinged by allegations of police misconduct and incompetence, many in the mid-1980s under the leadership of police commander Jon Burge, who has since retired.

"It is now common knowledge," a district court judge, Milton Shadur, wrote in 1999, "that Jon Burge and many officers working under him regularly engaged in the physical abuse and torture of prisoners to extract confessions ... as an established practice, not just on an isolated basis."

Chicago has already paid out more than $1m in civil damages for abuse cases, including some on Mr Burge's watch.

But it was not judges or lawyers or internal police conduct investigators, or even hardbitten Chicago reporters, who exposed the case that finally changed Mr Ryan's mind.

Anthony Porter, sentenced to death in 1972 for the murder of two teenagers, was freed in 1999 as a result of work by journalism undergraduates at the city's Northwestern University. He was days from execution.

"They asked me what I wanted for my last meal," he recalls. "I am a witness now to everybody on death row, and I ask the governor to do the right thing."

The governor told reporters: "My concern is not just with the death penalty as a singular issue. It's with the entire criminal justice system. If innocent people are sentenced to death - cases that get all kinds of scrutiny - what does that say about invisible, low-level cases - drugs cases and so on?"

Life or death decision

Gary Gauger is another exonerated prisoner. He was convicted of killing his parents, when the evidence did not seem to point at his guilt. He was released in 1996, but only finally pardoned by the state a fortnight ago.

He says he understands why some death row prisoners have said they don't want commutations of their punishment - only exoneration, or death.

"When I was first arrested, I thought, death sentence or life sentence, it doesn't make any difference now. Who wants to spend their life behind bars? But I learned there is life behind bars. You have to look for it, but it's there."

Appalled at the number of overturned convictions, the governor also appointed a commission to review the state's laws.

Last month, Illinois concluded several weeks of clemency hearings marked by emotional rawness, as victims' families heard convicted killers plead for mercy and made opposing arguments.

"If you are having trouble finding someone to pull the switch, to make the injection, to shoot him, I volunteer," Sam Evans told the hearing. He was referring to Fedell Caffey, found guilty of killing his daughter Debra and two of her children, then cutting a full-term foetus from her womb.

"I'll kill him myself if it's a problem for this state, this governor."

The governor's commission ended in tough recommendations for reform, though not for abolition. Scott Turow, the Chicago lawyer also known as the author of legal thrillers including Presumed Innocent, found the time he served on the commission sapped him of his certainty that some executions could be justified.

Mr Turow said: "Can the system possibly give us outcomes that go far enough to give us the confidence required to take a citizen's life? Our propensity to convict the innocent suggests not.

"Citizens can very easily criticise politicians, but all I can say is that the governor has a hell of a decision on his hands. All of the conflicting and highly emotional forces in this debate are weighing on him now."

Even committed death-penalty opponents have cautiously welcomed the way Mr Ryan has temporarily shifted the debate from the deadlocked issue of principle - whether it is right to kill even an unequivocally guilty murderer - to the practical question of whether the state's convicted murderers are guilty at all.

Mr Ryan's incoming Democratic successor, Rod Blagojevich, has indicated that he will continue the moratorium.

"The governor's been on his own journey," said Jane Bowman, the executive director of the Illinois Coalition Against the Death Penalty.

"If he grants commutations it will be a remarkable recognition that the system is deeply flawed."

Meanwhile, Howard's mother, Jeanette Johnson, racked with arthritis, took to her bed this week as she waited for Mr Ryan to pronounce on whether her son will live or die.