Enlarge Family photograph via AP Five-month-old Sabrina Paige Aisenberg was reported kidnapped Nov. 24, 1997, from her Brandon, Fla., home. Sabrina was first noticed missing when her mother went to check on her around 6 a.m. Stephen Kunz 1999 photo by Thomas M. Goethe, St. Petersburg Times Enlarge By Chris O'Meara, AP Marlene and Steven Aisenberg walk to Tampa's courthouse in 2000. The government dropped the criminal charges against them just before the scheduled tiral date. Barry Cohen 2008 photo by Chris O'Meara, AP

TAMPA  What happened to the baby girl is a mystery.

What happened to the federal prosecutor who handled the case against Sabrina Aisenberg's parents is not: A Justice Department inquiry found that he recklessly broke the rules when he charged them with lying about her disappearance.

The Florida Bar admonished the prosecutor, Stephen Kunz. The government dropped its case against Sabrina's parents, and paid defense lawyers nearly $1.5 million, the largest such sanction ever imposed against the Justice Department for its mishandling of a criminal case. And Kunz lost his position handling criminal cases for the U.S. Attorney's Office here.

"I told him, 'You're not going to be a criminal prosecutor here,' " former U.S. attorney Paul Perez recalls. Instead, Perez says he gave Kunz a choice: work on a team that handled civil lawsuits or look for a new job. Kunz soon found a job 200 miles away in Tallahassee.

As a federal prosecutor.

The episode — which unfolded over eight years beginning in 1997 — offers a rare window into the U.S. Justice Department's effort to police abuses by the lawyers in charge of enforcing the nation's laws. A USA TODAY investigation has found that prosecutors have little reason to fear losing their jobs, even if they violate laws or constitutional safeguards designed to ensure the justice system is fair.

Justice Department officials say they take every violation of those rules seriously. But USA TODAY's investigation, based on an examination of tens of thousands of pages of court files and reviewed by a panel of legal experts, found:

JUSTICE IN BALANCE: Prosecutors' conduct can tip the scales

FULL COVERAGE: Federal prosecutors series

• The Justice Department often classifies as mistakes violations that result in overturned convictions. Even when judges have cited prosecutors for flouting constitutional rules, the government often clears the attorneys of wrongdoing and concludes the violations were unintentional. The agency's internal ethics watchdog, the Office of Professional Responsibility (OPR), found wrongdoing in about one-quarter of the roughly 750complaints it investigated during the past decade.

• Even when investigators conclude that prosecutors committed misconduct, they are unlikely to be fired. Department records suggest that violations more often result in reprimands, suspensions or agreements that allow lawyers to leave the government with their reputations intact and their records unblemished.

After a judge in Massachusetts freed two convicted Mafia figures from prison because of " extremely serious government misconduct" by the lead prosecutor, for example, officials gave the prosecutor a written reprimand. U.S. District Judge Mark Wolf wrote in a 2008 letter to then-attorney general Michael Mukasey that the episode — which occurred before Mukasey became attorney general — "raises serious questions about whether judges should continue to rely upon the Department to investigate and sanction misconduct by federal prosecutors."

• The Justice Department consistently conceals its own investigations of misconduct from the public. Officials say privacy laws prevent them from revealing any details of their investigations. That secrecy, however, makes it almost impossible to assess the full extent and impact of misconduct by prosecutors or the effectiveness of the department's attempts to deter it.

A spokeswoman for the Justice Department, Tracy Schmaler, said in a statement that USA TODAY's "selective review of a handful of the many thousands of cases stretching back as far as 18 years does little to provide an accurate and representative picture of the honorable work done by federal prosecutors in courtrooms every day across the country." She said that "when mistakes occur, we correct them as quickly and transparently as possible within the bounds of the law."

Attorney General Eric Holder, who took over the Justice Department in 2009, has said the agency is moving to make sure it can more effectively prevent misconduct and better train prosecutors about the complex rules they must follow. The changes, including new training and policies, followed the failed corruption case against former Alaska senator Ted Stevens.

For years, however, says Joseph diGenova, a former U.S. attorney in Washington, D.C., the bottom line was that the government allowed lawyers "who should not be federal prosecutors to continue in that role. The record on discipline is very, very poor. The history of serious discipline is basically non-existent."

USA TODAY's investigation documented 201 cases since 1997 in which courts found that federal prosecutors violated laws or ethics rules. Although those violations occurred in no more than a tiny fraction of the tens of thousands of criminal cases filed in federal courts every year, each one was so serious that judges overturned convictions, threw out charges or rebuked prosecutors for misconduct. The violations put innocent people in jail, set guilty people free and cost millions of dollars in legal fees.

Without stronger safeguards, Justice Department critics say, those problems will continue.

"It's a disgrace to the Department of Justice, it's a disgrace to the system, it's a disgrace to what we're supposed to stand for," says Barry Cohen, the Tampa defense attorney who represented Sabrina Aisenberg's parents. He says Kunz, the prosecutor, should have been fired —— and prosecuted.

Both Kunz and his current boss, U.S. Attorney Pamela Marsh in Tallahassee, did not respond to requests for interviews USA TODAY sent to an office spokesman.

The missing girl

Sabrina Aisenberg was 5 months old when she disappeared from her crib one night in November 1997.

The story her parents, Steven and Marlene Aisenberg, told the police was horrifying: They awoke that morning to find their daughter's crib empty and their back door ajar. The authorities searched everywhere for the missing baby, scouring the area near her home in Valrico, Fla., outside Tampa, seeking any clue that could tell them where she had gone. They found nothing.

Eventually, investigators focused their suspicions on the girl's parents. Investigators from the Hillsborough County Sheriff's Office got warrants to secretly install listening devices in their bedroom and kitchen, recording thousands of conversations over three months. State prosecutors nonetheless concluded that they did not have enough evidence to prosecute the couple. But in 1999, almost two years after Sabrina vanished, federal prosecutors announced that they had solved the girl's mysterious disappearance, and charged the Aisenbergs with conspiracy and lying to investigators.

The recordings were the most damning evidence. On one, prosecutors told a grand jury and a magistrate judge, Marlene Aisenberg could be heard telling her husband: "The baby's dead and buried. … The baby's dead no matter what you say — you just did it."

But there was a problem with the recordings: Almost everyone who listened to them concluded that they didn't actually contain the statements prosecutors had presented to the grand jury that indicted the couple. U.S. District Judge Steven Merryday listened to the tapes and said he couldn't hear the incriminating statements. Perez, the former U.S. attorney, said he couldn't find them, either — even though the prosecutors, led by Kunz, had assured the court that the statements were there.

After a judge ruled the tapes inadmissible, the Justice Department took the unusual step of withdrawing the charges against the Aisenbergs before their trial began. Then it conceded in court that it should pay their legal bills under a law known as the Hyde Amendment, which requires the government to compensate people if the charges against them were "vexatious." The department ultimately paid $1,494,650.

OPR investigated Kunz's handling of the Aisenberg case. Its report — never made public, but summarized in state bar records— concluded that Kunz had recklessly tried to inflame the grand jury against the Aisenbergs and included unreliable excerpts from the recordings in the indictment. But its investigation also rejected Merryday's finding that the decision to charge the Aisenbergs had been "vexatious" or undertaken in "bad faith."

Kunz's bosses at the U.S. Attorney's Office stripped him of his position as a supervisor while OPR investigated. In 2002, Perez — who once had counted Kunz as a mentor — reassigned him to the civil division before Kunz eventually quit. The Florida Bar, which regulates lawyers in the state, publicly admonished Kunz in 2005, the mildest form of public discipline it could impose but nonetheless an uncommon rebuke for a federal prosecutor. Justice Department records show Kunz has been assigned to criminal cases in Tallahassee since 2003.

"It's kind of a travesty," said Steven Aisenberg, Sabrina's father, who lives in Maryland with his wife and two other children. Kunz "fabricated information, and he still has a job doing what he did before. Now he lives to do it again, to somebody else."

Aisenberg said the family is still searching for Sabrina. She would have turned 13 last June.

The watchdog

The Office of Professional Responsibility was founded in 1975 as part of an effort to restore public confidence after the Watergate scandal. Criticism soon followed. In 1990, for example, a congressional committee blasted the office, saying it failed to investigate some judicial findings that prosecutors had committed misconduct.

OPR's founder, Michael Shaheen, retired in 1997 amid an investigation by the Justice Department's Inspector General that ultimately concluded he and two top deputies had themselves committed misconduct by violating government travel regulations. Before he died in 2007, Shaheen told National Public Radio that OPR should be abolished, because it was "plagued by a history of delays and the bureaucratic layers superimposed on it, and by the end of an investigation — two, three years — you find that they've labored and brought forth … a squeak, or a mouse."

OPR's records bear that out. Its investigations, run by agency attorneys, typically take at least a year to complete, and dozens have gone on for more than two years, a USA TODAY analysis of data obtained from the office shows. The vast majority of those investigations conclude that prosecutors did not break the rules, or that any violations were unintentional and should not be punished.

From 2000 to 2009, OPR's annual reports show, the office completed investigations of 756 complaints — fewer than 10% of the total complaints it received — and found that lawyers had actually committed misconduct in 196 cases.

"Government lawyers are likely to view the conduct most favorably to other government lawyers," says Ellen Yaroshefsky, the head of Cardozo Law School's Jacob Burns Ethics Center in New York. She said an outside watchdog is needed. "It's human nature that you're going to give the person the benefit of the doubt, because it could be you next. There just needs to be an independent evaluation of allegations of misconduct."

Records show the Justice Department has cleared prosecutors even when courts found problems. For example:

•A court in Pennsylvania rejected an inmate's death sentence for torturing, then killing his cellmate because the prosecutor never disclosed evidence the inmate could have used to challenge the allegation that he had planned the murder in advance. OPR, disagreeing with the court, found that the prosecutor did not commit misconduct and was not required to turn over the evidence.

•A federal appeals court overturned a man's conviction for a Tennessee bank robbery because it found the prosecutor "clearly misrepresented" evidence to the jury in "deliberate disregard of his duty," the court said. OPR disagreed, saying the prosecutor had made a mistake, not committed misconduct, according to an analysis for the American Civil Liberties Union.

"It's just astonishing to me that the system over there just flouts federal appellate courts' findings — in some instances even disagreeing that it's misconduct at all, let alone how serious it is," says Richard Strafer, a Miami lawyer who conducted the ACLU's review.

A House oversight committee leveled a similar complaint in a report two decades ago, noting that Justice "has not provided an explanation for its disagreement with the judge's findings."

OPR takes that approach because its investigations focus as much on why a prosecutor broke the rules as they do on whether there was a violation. The Justice Department cites its attorneys for misconduct only when it can prove the violations were either intentional or reckless. More often, records show, it concludes that violations were the result of poor judgment, inexperience or excusable mistakes. In addition, OPR sometimes disputes courts' interpretations of the complex rules prosecutors must follow.

When it finds misconduct, OPR can only recommend a range of disciplinary penalties — for example, from 5 to 15 days' suspension without pay — but cannot impose the punishment itself. The recommendations go to the U.S. Attorney in the area where the prosecutor works. The penalty is imposed by the prosecutor's supervisor, but can be appealed to the deputy attorney general, the No. 2 official at Justice, and in some situations to an outside board. It can be a lengthy process.

The Justice Department would not release a complete list of disciplinary actions it has taken to punish misconduct; USA TODAY first asked for one in May 2009. The department's annual reports, which summarize some of the cases it investigated, suggest that lawyers are seldom fired for mishandling criminal cases. In the past decade, the agency's annual reports have disclosed only one instance in which a lawyer was terminated: a 2009 investigation that showed the Department of Justice attorney had been unlicensed for more than five years and had filed false certifications that hid the truth. In four other cases, OPR reported that it recommended termination, but the lawyers either resigned or retired.

Leslie Griffin, who worked as an attorney at OPR in the late 1990s and now teaches at the University of Houston, said the office has an "almost impossible job" because it is expected to police its own lawyers, protect their privacy and satisfy the public. "Self-policing never works," she said. "That's part of the problem. Do we really think that doctors police their own very well? No."

Trouble in Washington, D.C.

By the early 1990s, gang violence had turned murder into an almost daily event in Washington, D.C. Unlike other parts of the country, where homicides and other violent crimes are handled by state prosecutors, the job of putting Washington's killers in prison falls to the Justice Department. Many of the toughest cases ended up on the desk of G. Paul Howes.

In 1996, Holder, then the U.S. attorney in Washington, asked OPR to investigate Howes' prosecution of four members of a gang known as the Newton Street Crew. The probe lasted two years. OPR concluded that Howes had improperly given tens of thousands of dollars' worth of government witness vouchers to relatives and girlfriends of people who helped him build his case.

The Justice Department maintains that such intentional abuses are rare. But former OPR lawyers and outside investigators have said the agency overlooks some wrongdoing. One reason: Even when OPR finds that a prosecutor committed misconduct in one case, its investigators do not always look to see whether any of the prosecutor's other cases were compromised. Griffin says it's important that officials not "overinvestigate" prosecutors because of a single mistake, but the result is that the department can't detect the full extent of misconduct. It didn't in Howes' case.

If OPR had looked more deeply, it would have unearthed what the D.C. Bar Counsel's office later found when it conducted its own investigation: additional vouchers Howes had improperly approved for witnesses in another homicide. Instead of investigating further, the Justice Department spent two years fighting to keep its file on Howes from reaching defense attorneys in that case.

When a federal judge ordered Justice to release its findings in 2003, prosecutors agreed to shorten three other murderers' sentences. This year, attorneys for another man Howes prosecuted asked the D.C. Court of Appeals to throw out his conviction because of the payments.

The court also is considering whether to disbar Howes, who declined to comment. He left the Justice Department in 1995 and went on to represent Enron investors in a multibillion-dollar lawsuit. Howes testified in Washington's Superior Court in 2007 — in another hearing questioning his use of vouchers — that he "never went to trial with anybody that I did not think was guilty."

'A black hole'

The Justice Department refuses to discuss its misconduct investigations, though Congress has repeatedly urged more transparency. In 1978, for example, Congress asked the department to make the results of its investigations public. That happened for roughly seven years under Attorney General Janet Reno, President Bill Clinton's appointee, when OPR released summaries of its investigations that included prosecutors' names.

But — with the exception of a few investigations of high-ranking officials — OPR has not revealed the names of prosecutors it found committed misconduct in almost a decade. Justice officials told USA TODAY that a federal law known as the Privacy Act, enacted in 1974, bars them from releasing any details, even when the problems have been widely publicized. Instead, it produces anonymous annual reports without any identifying details, even genders, of the prosecutors involved.

"OPR is a black hole. Stuff goes in, nothing comes out," said Jim Lavine, the president of the National Association of Criminal Defense Lawyers. "The public, the defense attorneys and the judiciary have lost respect for the government's ability to police themselves."

OPR's former director, Mary Patrice Brown, who recently took a new job in the criminal division, said the office is considering taking additional steps to disclose the results of its investigations. The office also has caught up on its annual reports, which had been several years behind, and the summaries are more detailed than in the past.

It's not just its own files that the department keeps secret. In some cases, it has asked judges to expunge misconduct findings from public court records.

Two years ago, for instance, a federal judge in San Diego overturned a guilty verdict in a drug case against Kellie Shaver because the prosecutor who handled her case, Christopher Ott, never told the court that a witness had raised questions about some of the evidence he relied on during Shaver's trial. Prosecutors didn't quarrel with the court's ruling that Shaver's trial had been unfair — but they asked the judge to leave Ott's name out of it. Prosecutors also cut a deal with Shaver: She could plead guilty and go free immediately. In return, her lawyers couldn't oppose their request to conceal Ott's name.

Ott, now a federal prosecutor in Central Islip, N.Y., declined to comment, through a spokesman.

The prosecutor who negotiated Shaver's plea, Stewart Young, said Ott was not involved in the agreement. The Justice Department's investigation of the case is confidential.