Ira Johnson was unlike anyone I had ever met. Something about him left you uneasy, as if he knew who you were without asking. He could look right through you, dismiss you, even as you sat in front of him. He was a strange mix of danger and aloofness, the way his legs twitched under the table, the way he leaned so far back in his chair. He would smile, then jingle the handcuffs hanging from his wrists. Something about him, about the way he stared at your back when you turned around, something about him was evil.

He had killed, and he watched while his friends killed. And yet months later this same man would lean across a table in an Illinois prison and confess to an unspeakable crime so that four men wrongfully convicted -- two sent to death row -- wouldn't die for what he had done.

Ira Johnson, 36, with dark eyes and calloused hands, was already serving time for murdering a woman in a drug deal gone bad. But this was different. He could get the death penalty for acknowledging what happened one night in early May 1978. And he knew it.

My partner and I, two students from Northwestern University, were there hoping to find information about a brutal kidnapping, rape and double murder of a man and his fiancee. It was 1996, 18 years since they had been killed, and yet nothing about the case seemed settled. It lingered in the courts like a bad taste no one wanted to talk about and no one wanted to remember.

Ira Johnson was the only person alive who could put the pieces together. And as he sat at the table struggling between good and bad, between doing the right thing and telling us to go to hell, it struck me that he was the final paradox in a story that began in violence, corruption and racism on the South Side of Chicago, and ended in the hands of the unlikeliest heroes.

For the three of us -- Stacey Delo, Stephanie Goldstein and me -- the case started as a senior-year class project.

Our investigative journalism professor, David Protess, an anti-death penalty advocate experienced in examining wrongful convictions, instructed us to pick a case from a stack he had collected, and learn something about the criminal justice system.

It consumed us, from the minute we began reading, and quickly led us from the comfortable world of academia to Chicago crack houses, sheriff's offices, public housing and Illinois' death row.

On the first day of class, January 3, 1996, we chose the 1978 murder.

Twenty-six-year-old Larry Lionberg, a clerk at a South Side gas station, and his fiancee, 23-year-old Carol Schmal, a student, had been kidnapped from the station at about 10:30 p.m., the yogurt she brought him half-eaten on the counter. Their bodies were found the next day in Ford Heights, a poor, predominantly black neighborhood south of Chicago. Carol's body lay on the floor of an abandoned townhouse, Larry's in a creek bed 100 yards behind the house.

In the course of our six-month investigation, those were the only details of the crime that never changed.

Within hours of the discovery, the Ford Heights Police Department and the Cook County Sheriff's Office picked up four black teen-agers, walking them before television cameras, promising Chicago that the people who killed Larry and Carol were behind bars. According to court records, the reason for their arrest was that they were from the neighborhood and had visited the crime scene.

But four days after the teens' arrests, police said they had found an eyewitness and had taken her before a grand jury.

Within a year, the suspects -- Dennis Williams, Kenny Adams, Verneal Jimmerson and Willie Rainge -- were tried and convicted. Good kids from a rough part of town, they were loved by their families and friends. Only one of them, Williams, had a juvenile record, for setting a motorcyle on fire years before.

Now Williams was on death row, and Adams and Rainge were serving life terms. Stephanie, Stacey and I decided to visit them, and went to meet with lawyers from a small Chicago law firm representing Jimmerson, also on death row.

The men said they didn't do it and didn't know who had. I wasn't entirely convinced. Could so many people -- police, prosecutors and the jury -- all be wrong? My mind changed after we interviewed Paula Gray, the officers' eyewitness, and the heart of the state's case.

With the help of a paralegal working on Jimmerson's case, we found Gray in a South Side public housing complex. She was 17 at the time of the slayings and mildly retarded, with an IQ of around 65.

When we went to Gray's apartment, we found a 34-year-old woman sullen and withdrawn. Stacey and I stood outside her apartment door and told her how we had met Dennis Williams and Kenny Adams, who a lifetime ago had been her close friends. We said they had a message for her. She said we could come in.

Williams and Adams had told us to tell her that they didn't blame her, that she was a victim, too. Paula began to cry. She stared at the shag carpeting and kept pulling at the loose string on the armrest of her couch.

She had made up the whole story, she said. She had lied. The police had told her she would go to jail for the rest of her life if she didn't.

They kept her in a hotel room for three days after the crime, Gray said, cut off from her family and community. She said the police told her that they had fingered her friends as the killers, and unless she cooperated, she would go down with them. The police took her to the scene, to where the man's body was found, and told her how he had been shot, she told us. The police told her details of the crime until she repeated them, and then brought her before the grand jury to say them again. Then they let her go home.

By the time the defendants were on trial, she understood the gravity of their situation. She refused to testify against them, but prosecutors read her grand jury testimony into the record, and it was enough. The jury convicted the four defendants. Then prosecutors tried and convicted Gray of perjury. She spent eight years in prison.

In her apartment 18 years after the crime, Gray broke down as she recounted the story. Over and over, she kept saying she was sorry.

As Stacey and I sat in her tidy apartment with matching furniture, we looked at each other. They didn't do it. Eighteen years in prison, and they didn't do it.

More pressing, however, was the realization that Williams' execution date was to be set within six months, which meant that he'd probably be executed in less than a year.

We searched the case files and interviewed retired police officers, the few who would talk to us. Our professor began passing along what we learned to local media.

One afternoon in late January, as two of us sifted through a dozen boxes of case files stacked in a downtown Chicago office building, we found an envelope containing three pieces of paper. They were a police officer's handwritten notes made three days after the killings as three officers interviewed a man named Marvin Simpson. Simpson told the officers he knew the identities of the murderers because he was with them before the killings occurred.

"On Wednesday night, 10 May 78, at approx. 2030 hrs, Marvin, Dennis, Ira, Arthur (Red) and Johnnie were sitting around by Marvin's mother's crib. ... Dennis started talking about doing a score," wrote one of the officers.

Simpson went on to tell the officers that Red had told him exactly what they had done -- that they had raped the "White broad and [Red] had a knot of money in his pocket" as proof.

The four names scratched in pen across the top of the first sheet were Arthur "Red" Robinson, Johnnie Rodriguez, Dennis Johnson and Ira Johnson.

We knew we had to find them.

Our professor found a man named Renee Brown, who was familiar with the case from work he did for one of the convicted men's families in the early 1980s.

Renee was the one who found Arthur "Red" Robinson. Living in a slum neighborhood on the South Side, addicted to drugs, jobless, and almost illiterate, Robinson had spent the last 20 years in and out of jail, or living with relatives.

Sometimes one of us, sometimes all three, would drive down to Ford Heights with Renee and take people in the neighborhood to lunch. So would our professor. We took all kinds of people to lunch. I often felt like a traveling food train.

But food was how we got to know people. Eventually, I think, some of them even began to trust us. And usually Robinson came along. During the first three months we'd venture down to the neighborhood, Robinson never said a word.

I brought the case up once to him. Across the table over soup. He just stared at me.

Some people in the neighborhood said not to try to find Johnnie Rodriguez. They said he was very dangerous, in gangs. We crossed him off the list.

Dennis Johnson, it turns out, was dead. He had died of a drug overdose in 1993. Most people seemed pretty glad about that.

And then there was Dennis' younger brother, Ira Johnson. The division of corrections reported back that he was in a prison just north of the Illinois-Missouri border. About the time we started spending our afternoons in Ford Heights, Ira Johnson agreed to let us come visit him.

On a cold day in late February, Stacey and I walked into Menard Correctional Center -- the same complex where Dennis Williams sat on death row. Prison officials said we could talk to him only at a table in the warden's office. It was clear the guards didn't like us talking to him anywhere. I always understood this to be a matter of guards not wanting prisoners to get undue attention or special visits.

But it was also clear that Johnson didn't like talking to us, either. At least not about anything we wanted to hear. He worked us in circles. We came down with all these ridiculous conversation topics our professor had prepared for us -- about how bad cops are, about his childhood. As if Johnson was going to feel some kind of kinship with us, three white college kids from an expensive university.

I remember looking at the sheet of notes in front of me and feeling naive. After about an hour of nothing, we shut off our tape recorder. I closed my notebook and leaned as far back in my chair as he was in his. I told him about a party I went to two nights before. This story he liked. He wanted to know how many people were there, what music was played, what we did. I was 22, and he was 36, and the only thing I could find in common with this man was drinking 40-ouncers of beer.

Disheartened by the visit, Stacey and I decided to leave. But as we walked out the door, Stacey stopped in front of him. "We're giving you a chance here to do one thing right in your life," she told him. "Your brother would have wanted you to take it."

What the hell, I thought as she said it. It's worth a shot.

A couple of days later, we received vile letters from Ira, discussing Stacey's "bedroom eyes" and what he would like to do to her, or to me if Stacey wasn't available. We would have dropped him entirely had it not been for the final paragraph:

"Laura, think about getting what you been trying to find out. For years you know them boys didn't do that s--- and I know this also. But I'm not going to put myself in that situation. What the f--- am I getting out of telling. But they didn't do it so you and Stacey think about what I said. It's going to take some time for me to think this s--- over."

Those words were our entry into the real life of Ira Johnson. We wrote him back a curt letter telling him we were interested in some of what he had to say. He followed with another letter asking us to visit again.

He wrote, "I'm not just trying to get Stacey back down for no reason. I hate to see the boys suffer like this. I won't be able to function if them boys die for some s--- they didn't do. So it's up to you and Stacey if you want to help them or not."

Each time we returned to visit, Johnson seemed quieter. During the weeks that followed, through letters and talking, we began to learn things about Ira Johnson, that he and his brother sold drugs to Ford Heights police officers, that he and his brother shared a bond. Finally, on our second-to-last visit, we learned that his brother had been one of the killers.

Meanwhile, our professor in Chicago had found pro-bono attorneys for the four convicted men. They began pressing their cases in earnest, all at different stages of the appeals process. Public pressure, from the newspaper columns and television reports using our information and taped interviews, was mounting. My professor and Renee went in search of the three officers who were there when Marvin Simpson told what he knew.

Simpson lived two streets over from Robinson, and repeated to us what the officers had put in the handwritten notes. Two of the officers, Lt. Howard Vanick and Investigator David Capelli, refused to speak with us, but the third, George Nance, did.

Now retired and still living on the South Side, Nance was the only African-American police officer in the department in 1978. He said he has always known that the four convicted men didn't do it. But there was nothing he could have done to save them. He said he didn't have that kind of weight with his fellow officers or bosses.

He remembered the Simpson interview well. He said that after the interview, he, Capelli and Vanick all agreed that the information was a "serious lead." But after turning his notes over to his superior, they were never mentioned again. He didn't know why. He said this was the first time anyone had asked him about the case.

Nance took the notes while Chicago prosecutors were bringing Gray before the grand jury. If someone else had committed the crime, how could the department come forward and say they had the wrong guys? How would they explain Gray?

Even two decades later, one of the sheriff's deputies involved in the Paula Gray interviews, a man who would speak to us at dawn in his office before anyone came to work, knew he had to stand by the original story. Lt. James Houlihan would tell us a lot about the case, but he would never talk about Gray.

One day in late April 1996, while Renee, Stephanie and I were on a futile search for the murder weapon, Robinson came close to confessing. Renee had taken Robinson and some other lunch regulars out to eat at a local bar. One of them was David Campbell, a friend of Robinson's, who was also at Marvin Simpson's house the night of the crime and heard them talking about a score. For several weeks before the lunch, he had been working on Robinson, telling him he should come clean.

When Stephanie and I joined them at the bar, Renee came to the door and told us he thought Robinson was ready to talk.

A lot of what he said made no sense. He seemed to be confusing different crimes, undecided about whether drug debts were involved or whether it had been just to steal money. But he did say he said he was there that night when they kidnapped the people from the gas station, but that he had run out of the townhouse before the two were killed. He claimed that Ira and his brother raped and shot the woman.

We started the tape recorder and made out an affidavit to give to the attorneys. A crew from the local television station and a columnist came down the next day to interview him.

Stacey and I went back to prison to see Ira. This time, we met in the prison visiting room, a large, open area with cheap, cafeteria-like tables. Ira was waiting for us.

"What did Red [Robinson] say?" he asked, wasting no time.

"He told us everything. He told us you raped and shot Carol," I said.

He looked across the table and said, "Red's lying."

Then maybe it's time you tell us what really happened, Stacey answered.

Ira began talking casually, saying he and his brother had met up with Johnnie Rodriguez and "Red" Robinson late in the evening of May 10, 1978. When they pulled into the gas station, they were planning only to rob it.

But his brother liked the girl, he said, so Dennis put a gun to her head and made her get in the car. They couldn't leave the guy behind.

With Carol in the front seat and Larry in the rear of the gray Buick, they drove. Ira said they drove for more than an hour, trying to figure out where to take their victims. The longer they drove, the deeper involved they became.

In the end, they took them to a place they knew, the abandoned townhouses near their neighborhood. They forced Carol and Larry into the house, he said, and brought Carol upstairs. Ira said they forced Larry to watch while Dennis Johnson and Robinson raped her. Dennis then shot her execution-style while she was on her knees, and told Robinson to shoot her, too.

Ira Johnson said his brother was worried one of the four of them would tell, so he made sure everyone took part in the crime. He told Ira and Johnnie Rodriguez to take Larry outside.

Ira said Larry got up and started walking. He kept on walking, through the yard, through the field outside, until he reached the creek's edge. Then he stopped.

Larry never said a word to Ira. He never tried to run. He never fought back. He never even turned around.

Ira said he held up his gun and shot Larry in the back of the head.

Sitting at the table, Ira was barely whispering. He was so quiet. After that night, he said, the four of them vowed never to speak of any of it again. Ira had kept that promise. Until now.

Ira told us he had been a good kid, that he had just wanted to be like his brother. But that night he crossed a line.

I wondered what he was thinking as he sat across the table.

Could he see that I was just like her, that 23-year old student he watched his brother kill? Could he see that she was all I had thought about for six months, running over in my head what her last few hours had been like? Did he understand that she had a life? I don't know if he did. He never even knew her name.

And yet why was he telling us this? Why was he crying?

With the confessions of Ira and Robinson and a slew of other information that our professor, Renee and the attorneys had compiled before the courts, the district attorney's office agreed to submit a swab taken from Carol for DNA testing, which was unavailable in 1978.

Two weeks before we graduated, we got news that the tests exonerated the four convicted men. They later showed that Robinson and Dennis Johnson had raped Carol.

On the day we graduated, Williams, Adams, Rainge and Jimmerson were freed. The district attorney told them in a short statement that he was sorry.

They walked out of the courtroom with little education, no money, no skills and 18 years of their lives lost.

In Illinois, a person wrongfully incarcerated can receive a small stipend for every year of imprisonment. But the money caps out at $35,000.

On June 16, 1997, Ira Johnson and "Red" Robinson were charged with kidnapping and murder. Facing the death penalty, both pleaded guilty later that year and received life in prison without parole.

I testified at the trial of Johnnie Rodriguez, the supposedly dangerous drug lord the neighborhood people had told us not to look for. From the witness stand, I got my first glimpse of this man. As it turns out, our information about him was wrong. He had changed and had spent the past 18 years a quiet man married to the same woman, with children and a job.

The parents of Carol and Larry sat in the front row of the courtroom for the second time in their lives, holding their breath as the prosecutor described again what had happened to their children.

Rodriquez was convicted and is also serving life.

As for the four men, Williams works part-time with underprivileged teens in Chicago, Adams is married and works for United Parcel Service, and Rainge and Jimmerson are still trying to pull their lives together.

In March, Illinois paid them a total of $36 million -- the most ever in a wrongful-incarceration case in U.S. history -- to settle the civil suit the four filed against the state.

Though wrongful-incarceration suits are often difficult to win, Illinois probably did not want 20 years of dirty laundry from law-enforcement officers clouding the courtroom. The four men's attorneys alleged that the officers and the prosecutor in the case have a history of concealing evidence, stretching from before the 1978 killings to years after.

In the end, justice was done, the bad guys were sent away and the good guys were vindicated. But at such a cost. Four men lost 18 years because the system failed them, and it failed society. Four dangerous men remained on the streets.

I've heard people say that this case shows that the death penalty works because the condemned were proved innocent before it was too late. But Williams, Adams, Rainge and Jimmerson weren't freed because the system worked. They were freed because we got lucky. In a passing moment -- an interview not conducted with Paula, a different box of case files, a different conversation with Ira -- it would have ended another way.

Last year, Ira was diagnosed with cancer of the throat and lungs. He is not expected to live much longer.

He still writes to me sometimes, but I haven't written back. I'm just not sure what I would say.

LAURA SULLIVAN IS A REPORTER IN THE SUN'S ANNE ARUNDEL COUNTY BUREAU.