Sycamore, Illinois (CNN) The first thing Jack McCullough did as a free man was order a slice of pizza. For years, he'd practically drool every time a pizza commercial came on the tiny television in his cell at Illinois' Pontiac Correctional Center, where he was serving a life term for a 1957 cold case murder he's always insisted he didn't commit.

On Friday, a judge agreed that his murder trial had been so flawed that McCullough should go free. It took a minute for the news to register. When it did, McCullough sighed with relief and then grinned from ear to ear. He turned toward the muscular, shiny-pated man guarding him and raised his wrists, ready for unshackling. But he'd have to wait a little longer to be processed out of the system.

Two hours later, his stepdaughter, Janey O'Connor, was gunning a white rental car out of the parking lot of the jail across the street from the DeKalb County Courthouse. In the back seat was McCullough and Crystal Harrolle, the investigator from the public defender's office.

Harrolle had also been by McCullough's side in court in September 2012 when people stood and cheered the guilty verdict in what was touted as the oldest cold case to go to trial. Tears flooded his eyes as he recalled being told, afterward, how Harrolle walked out of court and sat in her car and cried. But she never gave up on him, and neither did O'Connor.

And so, heads spinning, they drove around the corner to World Famous Pizza, and McCullough bit into a slice of pepperoni. After years of prison food, including a meal he called "kinda pizza," it was the best thing he'd ever tasted.

"A guy came out of the Harley shop next door and he cranked it. And I said, 'Free-dom!' " McCullough paused and laughed, savoring the memory. "It was a wonderful feeling."

Read the original series on the case: "Taken" Maria Ridulph's murder went unsolved for half a century. Then detectives pursued a tip, and a man was brought to trial and convicted in the 1957 murder of the 7-year-old in Sycamore, Illinois. Now that man is free. Ann O'Neill's 2013 series on the case, "Taken," raised questions about whether the trial was unfairly one-sided.

McCullough was still riding the high a couple of hours later when he granted CNN his first, exclusive interview as a free man. He had spoken with the network once before, in prison shortly after his conviction, for the CNN digital series "Taken," which examined his murder trial and raised questions about whether it was fair.

This time, he was elated and a bit overwhelmed but didn't seem angry or bitter. Perhaps that will come later. But not now.

"I'm just perceiving everything. I'm seeing, I'm feeling, I'm talking," he said. "I am glad to be out. I feel compassion for the people who are still there. I just want them to know I didn't escape from anything. I wasn't guilty in the first place."

And so he persisted.

"I just never gave up. I knew I was innocent," he said. "I knew I had proof that I was innocent, and I was going to make them see the proof, one way or the other."

He seems in remarkably good shape for a 76-year-old, much less one who has been locked up since June 29, 2011 -- the day he was arrested in Seattle.

"I didn't think this day would come," he added. "I was beginning to believe I couldn't get justice in Illinois. But here it is."

Justice is still unfolding for McCullough. Although he is free, he technically could stand trial once again. But State's Attorney Richard Schmack, who is convinced McCullough is innocent , says he isn't finished with this case.

Schmack told CNN he will move early next week to dismiss the murder charge with prejudice, meaning nobody can ever again bring McCullough into court and accuse him of murdering his 7-year-old neighbor, Maria Ridulph.

And so, everybody returns to court on Friday. After that, McCullough may finally be free to return home to Seattle, where his wife, Sue, has been waiting for him.

"I've got another week to go to sort out whatever legal matters are pending, and then I can go home to my wife and start my life over and do as much good in life as I've got left," he said. "The next 10 years of my life are gonna be at 100 miles an hour because I've got a hell of a lot to do."

When CNN spoke with McCullough in prison, in March 2013, he was moved to tears just once, when he recalled his combat experience in Vietnam.

Now he gets misty-eyed often, usually while talking about the people who have helped him or stood by him. He is embarrassed by his tears, but powerless to stop them as he processes his newfound freedom.

A prosecution that 'went off the rails'

Jack McCullough's freedom didn't come as the result of legal razzle-dazzle, although at the end he was represented by a trio of lawyers from a top Chicago law firm.

McCullough calls them his "rock-star lawyers." But they were brought in late in the game to spiff up his own jailhouse lawyering.

He had exhausted all his appeals and didn't have a lawyer when he filed a handwritten petition prepared by another inmate with paralegal training.

That was in June, and a judge in Sycamore tossed his petition out of court, calling it "frivolous" and "without merit."

But it caught the attention of Harrolle and her boss, DeKalb Public Defender Tom McCulloch, who had represented McCullough at trial and believed he had been wrongfully convicted. Schmack, who knew he could eventually be tasked with defending the conviction, decided he'd better dig into the 4,500-page discovery file. It included old FBI, Illinois State Police and local and sheriff's investigative reports from 1957 and 1958.

Schmack took them home and started looking through them in his spare time.

He'd attended the trial in 2012; he was in private practice and running against State's Attorney Clay Campbell, who was personally prosecuting the case in court. Schmack told CNN he was troubled by how thin the evidence was.

McCullough, meanwhile, was undaunted. He filed a second handwritten petition on December 11. This time his former public defender joined in, saying that while the crafting of the do-it-yourself petition was "inartful," some of the issues raised had "constitutional merit." He asked the court to appoint a lawyer to help McCullough with his appeal. He even volunteered to do it himself.

The judge asked Schmack for a response to the petition. Schmack stunned everyone by filing a lengthy, heavily footnoted report that he said demonstrated "clear and convincing evidence" McCullough was innocent.

He attached exhibits supporting his footnotes -- grand jury transcripts and some of the FBI reports that had been barred from McCullough's trial.

As the appeal moved forward at the courthouse in Sycamore, it presented an ironic reverse scenario: An inmate's handwritten petition had resulted in a prosecutor admitting to nearly three dozen facts and allegations raised by the defendant.

"I was ordered to file an answer, and I could not file an answer that denied his claim of actual innocence when I actually believe he is not guilty of the crime he was convicted of," Schmack explained.

"The only question was whether I filed something very brief and cryptic or something more extensive. So my feeling was the public has the right to know why I was doing what I was doing, and why I was not answering this in the conventional way."

Chicago attorneys Gabe Fuentes and Shaun Van Horn, who work for a large, prestigious firm that seeks exoneration for wrongfully convicted defendants, agreed to represent McCullough through the rest of his appeal.

In court Friday, Fuentes -- a former federal prosecutor -- told Judge William Brady in no uncertain terms: "This was a prosecution that went off the rails. There are deep, deep problems with this case, which is why Mr. Schmack has come before this court with his report on those errors."

He went further by stating that the trial court and the appeals court were misled about the evidence against McCullough. At the trial, only a vague time frame was offered for when the little girl was abducted from a Sycamore street corner near her home. And, he said, evidence clearly establishing McCullough's whereabouts that evening was kept out of the trial.

That evidence supported the alibi McCullough had claimed all along.

Schmack cited an ethical code that became law in January. It lays on prosecutors a duty to undo wrongful convictions when they find them.

"Most people who are innocent and get exonerated in this country don't get exonerated on appeal," Schmack said Friday in court. "They get exonerated at proceedings like this. If the standard were that we can't look beyond the rulings that were made on appeal, they'd never be exonerated."

Brady, the judge, relied on three key items of evidence in throwing out McCullough's conviction. Two were discovered after the trial, and the other had been barred by a faulty evidentiary ruling at the trial.

Freshly subpoenaed phone records place the pay phone used for a 6:57 p.m. collect call to McCullough's parents at the post office in Rockford -- just where he said he was at the time the girl was snatched on December 3, 1957. The records support McCullough's alibi, which he was unable to present at his murder trial.

If McCullough was indeed 40 miles away from the crime scene, Brady said, it casts doubt on the testimony of Kathy Chapman, Maria's playmate. She picked McCullough out of a photo lineup some 50 years after the fact, saying he was the man who called himself "Johnny" and offered the girls piggyback rides minutes before Maria was last seen.

Brady also found that the trial and appeals courts did not yet know about an inmate's allegations that prosecutors offered him favorable treatment with his own case if he testified against McCullough.

"Those are matters that go to the heart of this prosecution," Brady said. Each, by itself, may not have affected the outcome of the trial, he added, but when viewed "collectively" make it unlikely that McCullough would have been convicted.

There was no one in court Friday to speak for the people who investigated and prosecuted the case against McCullough.

Campbell, the former state's attorney, and the Illinois State Police have declined repeated requests for comment.

The judge took pains to say on the record that he personally knows both Campbell and Schmack and doesn't view the controversy over the case as politically motivated.

Life behind bars

McCullough said nearly five years behind bars has led him to believe that at least 5% of his fellow inmates are not guilty.

But many of his fellow prisoners considered him guilty -- and for the worst of crimes. Making things even more dangerous for him in prison: his own law enforcement background.

"I'm a former policeman and a convicted child killer, and by extension they would think child molester, whatever," he said. "In prison, that's a death sentence."

A man must take precautions to stay safe. McCullough kept a low profile and worked at not offending anyone.

"I have spent all of my time in prison in protective custody with guards protecting me from the inmates. I refrained from going outside a lot, because outside is where you are with everybody and anybody can hand you something steely and unpleasant. So I stayed in my cell a lot -- not because I was afraid but because it was the smartest thing to do."

He was attacked by a cellmate during his first year in prison. The man stabbed him in the eye with the sharpened handle of a toothbrush. The next day, every toothbrush in the prison was confiscated.

He said he believes he was deliberately placed with a man who guards knew would attack him. But the inmate was a "small" guy and "he wasn't a threat to me if I'm awake," McCullough said. "But I'm asleep and he has a sharp object and he's stabbing me in the face and head and eye. I took two stitches to the back of my eye. I was a bloody mess, and the blood behind my eye pushed my eye out. I pushed my eye back in and blood squirted across the room. And I was just covered in blood.

"And what for? " he asked. "He wanted to blind me. He knew I loved to read." He praised the medical care he received, saying he eventually recovered his vision.

He showed off a semicircular scar on the meaty part of his hand.

"Those are teeth marks," he said. "When I snatched the toothbrush out of his hand, he grabbed my hand and bit me." McCullough tried to throw the toothbrush out of the cell, but it kept bouncing off the door. "So I kept kicking him until the guards came. Nobody was going to say a word. They usually just let fights go. But as soon as I said, 'He's stabbing me,' everybody showed up."

Prison is a cacophony of unpleasant sights and sounds, and the aroma of hundreds of men kept in close quarters can be overwhelming, McCullough says. He did what he could to preserve his own humanity. He snipped the wires off a pair of ear buds and used them to dull the sounds of men screaming. It didn't completely silence them, but at least he could no longer make out what they were saying.

And he sought solace in the prison library, where he says he could at least find some "intelligent people." He studied languages, including Mandarin and Japanese.

"When I first arrived in prison, everybody said, 'Go hit the law books.' Well, I'm not a lawyer. I don't want to be a lawyer, and I'm not going to get myself out of prison," he said. Instead, he befriended an inmate who had trained as a paralegal.

McCullough teared up as he described how the man helped him frame his appeals, even writing them out by hand in tidy block letters because there were no typewriters in the prison.

"He helped me, and he started to file motions for me, and the next thing I knew I was getting results," McCullough said. "And I'm tickled pink."

His attorneys have advised him not to talk to the media or discuss anything related to his court cases. But he places prosecutor Schmack in a different category. He was among the people who assisted him even though the prosecutor technically holds the power to put him back behind bars.

"People have to realize, it's not about winning. It's about justice. And this brave man -- I probably shouldn't talk about him at all -- but he put his career on the line for me," McCullough said. He thought a moment and carefully chose the words that followed:

"It isn't about winning a case, it's about justice. And God bless the man who stood up for justice. He's probably going to pay a penalty for that because to everyone else it's about winning. But it's not about winning. It's about doing the right thing."