This is Part 2 of a series. Read Part 1.

Among the thousands of prosecutors who have tried cases in the name of the people of New York City, Claude Stuart came to hold a handful of unfortunate distinctions:

• He was a serial abuser of his authority. State appellate courts reversed three convictions based on his wrongdoing.

• His misconduct actually led to disciplinary action by his superiors. He lost his job, and eventually his law license, after an appellate court determined he had lied to a judge about the whereabouts of a key witness.

• The particulars of his disciplinary proceedings became public, opening a window into the typically secretive panels that are supposed to police the state’s lawyers.

Stuart declined repeated requests for comment for this story.

It’s worth it, then, to appreciate the impact of Stuart’s career in greater detail, how the misconduct took place, how it has complicated the continuing pursuit of justice, and how the consequences of Stuart’s misconduct still linger, years after the man himself was exposed and disgraced.

The People v. Tyronne Johnson, Stuart’s last trial as a prosecutor in Queens, is a perfect case to trace those issues.

The Crime:

On Feb. 24, 2000, Queens prosecutors charged 23-year-old Tyronne Johnson with the murder of Leroy Vann. Three weeks earlier, Vann, an owner of a nightclub that Johnson frequented in Jamaica, Queens, had been shot in the stomach at 3:20 a.m. while standing in front of his home.

Vann stumbled inside, tumbled behind a couch and called for his elderly mother, Mary Puryear. His mother later testified that Vann had told her that a man named “Tyronne” from a nearby housing project had shot him in a botched robbery attempt with at least one other man, according to court records.

Police officer John Blandino said he interviewed Vann as an ambulance sped them to a local hospital.

“Leroy, listen here, you have a big hole in your chest,” Blandino said, according to court testimony. “There is a chance you might not make it, but let us catch this person that did this to you. Tell me about Tyronne.”

Vann, coughing and sputtering blood, repeated what he told his mother and added that Tyronne drove a white Lincoln Navigator, according to the officer.

When Johnson was questioned that morning, he volunteered to go to the precinct for questioning and told police he “wouldn’t shoot Leroy, he’s a friend,” according to court records. He was released after police interrogated him for several hours.

Two weeks later, Daniel Small, a man in police custody for a separate offense identified Johnson in a photo array, saying he had confessed the crime to him. Johnson was arrested days later. Thirteen years after that arrest, Johnson maintains what he asserted at the time: He had played no role in the killing.

The Trial:

By the time pre-trial proceedings began in spring 2002, Small had died.

Stuart, lacking any physical evidence, told the court and Johnson’s defense lawyer that he would rely chiefly on the testimony of Blandino and Puryear to make his case.

But the day before the trial, Stuart dropped what amounted to a bomb, telling the defense he intended to present a third witness: a 22-year-old man named Henry Hanley, who lived across the street from Vann and had fled when police first tried to interview him days after the murder.

Hanley was arrested in March 2000 on a probation violation and questioned about the murder. He said he was paid to be a lookout while Johnson and another man murdered Vann in an attempt to rob him. He agreed to testify against Johnson in exchange for a light sentence for his involvement.

Hanley wasn’t Stuart’s only late surprise. He also waited until just before trial to share with Johnson’s lawyer a potentially critical piece of evidence: the police statement of Shanise Knight, a relative of Hanley’s.

Knight had told investigators that she had seen a man confront Vann minutes before the shooting. She described the man as about 35 years old, six feet tall and 230 pounds. Johnson was 23, stood 5 feet, 6 inches, and had a much slighter build, weighing about 140 pounds. Knight had not identified Johnson when she was shown a photo array of possible suspects that included his picture.

Johnson’s lawyer, understandably, wanted to call Knight as a witness, but he could not locate her. He asked Stuart repeatedly during the trial if he knew where she was. Stuart said he didn’t.

Court records show that on June 4, 2002, Judge Jaime Rios, who was overseeing the trial, also asked Stuart if he knew where Knight was. Stuart again said he didn’t, adding that he, too, was trying to find her.

Johnson was convicted the next day of second-degree murder. He was sentenced to 20 years to life.

In an interview at Sing Sing Correctional Facility, Johnson’s face was grim when he recalled hearing the verdict read.

“I felt broken inside,” he said.

The Reversal:

The verdict was only hours old when Johnson’s family and lawyer set about mounting an appeal.

And it didn’t take long for that effort to provide a shocking revelation. Michael Race, a private investigator hired by the family, tracked down Knight. Knight, for the first time, told her story to Johnson’s side. And there was much more to it than she had initially told police.

Knight said she could discredit Hanley’s critical testimony. She told Johnson’s investigator that Hanley had been neither an accomplice to the crime nor a witness to it. She said he had been staying with her and was downstairs, asleep, when the shooting occurred. Knight said she woke him when she heard the gunshots. She ultimately signed an affidavit to that effect.

But she had one more explosive bit of information. She said in her sworn statement that Stuart not only had known where she was during the trial, but that he and two police detectives had visited her at her job just days before Stuart had insisted to Judge Rios that he did not know where she was.

More of Stuart’s case soon seemed to crumble, as well. When Race went to see Hanley in prison, Hanley signed an affidavit in which he recanted his trial testimony and alleged that he was pressured by Stuart to accuse Johnson.

“I did not witness this incident into the death of Leroy Vann,” Hanley’s affidavit said. “I want the court to know and understand what I have previously done was a great error.”

A television station aired an interview with Knight in which she described her meeting with Stuart. The segment also featured Hanley’s girlfriend, SharmaineRamdass, who confirmed that she and Hanley were asleep at the time of the murder.

Later that year, Stuart’s supervisors agreed to have Johnson’s conviction vacated. Queens District Attorney Richard Brown wrote a letter to Judge Rios saying as much, adding that Stuart’s conduct could not “be condoned.”

The Disciplinary Process:

It is impossible to know how many prosecutors get reported to the state’s disciplinary panels for alleged misconduct. What is clear is that the appellate judges who overturn convictions because of misconduct don’t routinely refer the offending prosecutors to the disciplinary committees. Defense lawyers, for their part, are often reluctant to complain formally, fearful that they will incur the wrath of prosecutors they will have to deal with again and again.

But Stuart’s conduct in the Johnson case did provoke a referral. The trial judge, after vacating the conviction, sent District Attorney Brown’s letter to the disciplinary panel, known formally as the Second Department Grievance Committee.

Brown had been blunt in his letter: He said Stuart’s handling of the Johnson case “was totally inconsistent with the high ethical standards that I expect from my assistants” and that his office would pursue an investigation. “If disciplinary action against the assistant is appropriate, it will be taken.”

Brown did act against Stuart, forcing his resignation.

When investigators with the disciplinary panel began to dig into Stuart’s record, they found he had actually been reprimanded years before for another flawed prosecution.

In 1995, Stuart insinuated that a gun in the possession of the defendant at the time of his arrest was the same gun used in an attempted murder and robbery. But Stuart had a ballistics report showing that wasn’t true: Bullet casings found at the scene of the crime didn’t match the gun.

The defendant, Jay Walters, was convicted and sentenced to up to 25 years in prison. He served nearly four years before his conviction was overturned by an appellate court, which found that Stuart advocated “a position which he knew to be false” -- an “abrogation of his responsibility as a prosecutor.”

The investigation of the 1995 case ended with the disciplinary panel issuing Stuart a so-called letter of caution warning him not to breach ethical boundaries again. It was never made public. Stuart’s bosses in the Queens District Attorney’s office say they did not know about it.

Years later, when the panel looking into the Johnson case asked about the Walters matter, Stuart blamed his misconduct on inexperience. He then asserted that in the Johnson case, while he should have acknowledged seeing the key missing witness, he did not intend to mislead the court.

“I certainly made an error or mistake in judgment,” he said. He claimed that he had telephoned Knight the day before he was asked about her whereabouts by Judge Rios, but that he had not reached her. He said he based his reply to the judge solely on that.

“I answered the question very narrowly,” he said.

Melissa Broder, counsel for the disciplinary committee, dismissed Stuart’s explanation.

Stuart had told the court a “flat-out lie,” she said, because he was afraid the witness’ testimony would undermine his case or that Rios would decide Stuart had withheld potentially exculpatory evidence.

In September 2005 – more than 18 months after it had opened its investigation of Stuart -- the committee suspended Stuart’s license to practice law.

After his resignation, he landed a job in private practice doing civil litigation, a job he then lost along with his license.

“I was disappointed that I had to let him go,” said David Brand, a partner at the Long Island firm Stuart had joined. “He was actually a good, effective trial lawyer.”

In March 2010, New York’s appellate division denied Stuart’s application to renew his law license, saying he “does not demonstrate the requisite fitness and character to practice law.”

Stuart – who still has an active license to practice law in New Jersey – today works as a math teacher at Queens Vocational and Technical High School.

Johnson, who remains to this day in a prison cell in part because of Stuart, said he feels sorry for the former prosecutor.

“I wish he just learned a lesson, but he didn’t have to pay for it with his whole career,” Johnson said of the severity of Stuart’s discipline. “You’re held to a high standard. Don’t set people up… if there is evidence of someone’s innocence, explore it… They know when something’s not right.”

The Retrial:

Eugene Reibstein, a high-level Queens assistant district attorney who had tried dozens of homicides and felonies, was tasked with mounting the second prosecution of Johnson in July 2003.

Reibstein visited Hanley in prison and got him to recant his recantation. Despite his sworn affidavit claiming he had lied at the first trial, Hanley told the same story again during the second trial.

This time, however, Johnson’s lawyer got to put Knight on the stand. She testified that Johnson couldn’t have been responsible for the crime because he was far smaller than the man she saw that night. She also stuck to her earlier sworn statements that Hanley, the alleged eyewitness, had been asleep in her apartment at the time of the shooting. Ramdass, Hanley’s girlfriend at the time, testified that she was in fact asleep with Hanley during the shooting.

It was not enough. Reibstein said that Knight and Ramdass were lying in his summation.

But ultimately it was Vann’s mother, Mary Puryear, who shifted the balance of the trial.

A New York Daily News story described the jury as “transfixed” when Puryear, Vann’s mother, testified from a wheelchair and tearfully described how Vann told her “Mama, I’ve been shot. Tyronne did it.’”

Johnson was convicted again and sentenced to 20 years to life.

The controversy around the case did not end there.

After the trial, Judge Rios’ law clerk wrote a letter to the New York State Commission on Judicial Conduct, accusing him of coaching the prosecution in private discussions during the second trial.

Johnson’s lawyers petitioned for yet another trial. At a hearing, Rios admitted to speaking to Reibstein in his chambers, but said he could not remember the details of the conversation.

Brooklyn Supreme Court Judge Matthew D’Emic ruled that while the conversation “strayed into improper territory,” it did not prejudice the verdict against Johnson.

Now 36, Johnson has spent the last 13 years behind bars. His lawyers maintain he never received a fair trial. And they have now applied to a federal court to grant him yet one more trial.

“It doesn’t get easier,” Johnson said in the interview at Sing Sing last year. “You see your Mom get old. You see your children getting older. Relationships fall apart. People die. It gets harder as you go along. My son was five years old when I got locked up. My son is 17 on Friday.”

If he’s eligible for parole, Johnson’s soonest possible release date would be in 2020. But to qualify, inmates usually have to express remorse for their crimes. He says he’ll never do that.

“I’ll never admit to something I didn’t have anything to do with.”

Sergio Hernandez, Melanie Hicken, and Aarti Shahani contributed to this report