In his campaign for county executive, Prince George's State's Attorney Jack B. Johnson has made much of his efforts to prosecute police misconduct. The Democrat calls himself "the only one" who has stood up to law enforcement misdeeds in a county beset by police scandals and long-standing allegations of brutality by officers.

Now, with the election days away, that claim is at the center of a debate about Johnson's performance in office.

Johnson has said repeatedly in interviews and campaign appearances that he has prosecuted police only when he saw evidence of criminal behavior. But many police officers and some defense attorneys accuse Johnson of prosecuting police on flimsy evidence for political gain. By charging officers, Johnson has been able to portray himself as tough on police misconduct, even if the charges had no merit, his detractors allege.

Whether Johnson was seeking justice, votes or both, his efforts to convict police officers have failed.

Since he became state's attorney in 1995, Johnson has had his prosecutors try seven cases of alleged police misconduct. Each time, the defendants were acquitted. All but one of the 11 officers Johnson prosecuted remain on the force; none was pushed out because of the criminal charges. Some were promoted after they were acquitted.

To be sure, Johnson's task was difficult: Convicting a police officer of official misconduct requires a virtually airtight prosecution, legal experts said.

Johnson has pursued many more police prosecutions than any of his predecessors. But Johnson's efforts, his detractors point out, have been marked by poor preparation, weak and contradictory evidence, questionable legal judgment, uncorroborated testimony from a single witness, a dearth of forensic and medical evidence and embarrassing courtroom missteps:

In one trial of an officer charged with assaulting a suspect, the star prosecution witness, also a police officer, testified that he never saw the defendant do anything wrong. In another case, a prosecutor told a judge that an officer charged with stealing jewelry and cash from a suspect should testify to prove his innocence -- an argument that ignored the Constitutional protection against self-incrimination.

Johnson declined verbal and two written requests to be interviewed for this report. In a voice mail message, Johnson said, "My response is this is old news. People have been talking about it for years. You have written about it. I don't see me adding anything to what the defense lawyers have been claiming. I'm not going to comment for this story, because I don't think it's worth it.

"People will always criticize. The fact that people who are not politically in line with my thoughts would say what they say is of no moment to me. The citizens know my reputation. They have spoken about the fact they have confidence in me, so there's nothing else for me to talk about."

Six of the seven police misconduct cases Johnson has brought involved allegations of excessive force. Those are the most difficult cases for a prosecutor to win, according to legal experts.

"Juries and judges tend to be very sympathetic to police officers and not so sympathetic to their accusers, who often have criminal records or were caught committing a crime," said Milwaukee County District Attorney E. Michael McCann, former chairman of the criminal justice section of the American Bar Association.

Rod Uphoff, associate dean and professor of law at the University of Missouri at Columbia, pointed out other hurdles.

"You've got a defendant who's likely to be well-represented, in contrast to other defendants who may have an overworked public defender or an attorney who doesn't have the resources to hire private investigators," Uphoff said. "That means the case will be harder to win right from the start."

Most of the 11 officers Johnson has prosecuted for official misconduct had powerhouse attorneys paid by the Fraternal Order of Police.

In six cases, the defendants chose to be tried by a judge instead of a jury. After a Circuit Court judge acquitted a Riverdale Park officer of assault charges in January, Johnson lashed out at county judges, saying they provided a "safe haven" for police misconduct.

But many of the defense attorneys who won their cases said it is not the judges, but Johnson, who is responsible for the string of acquittals.

"It doesn't happen that you lose this many cases as a fluke," said defense attorney Robert C. Bonsib, who has won acquittals in two police misconduct cases in the county.

"I think the pattern in many of these cases is Jack wants publicity for charging the officers and doesn't care what the outcome is," said Bonsib, who served as deputy state's attorney under Johnson's predecessor and worked with Johnson in the early and mid-1990s. "If he wins, he's a hero. If he loses, he can blame it on somebody else."

Cpl. Brian C. Catlett In September 2000, Johnson obtained a highly publicized indictment charging county police Cpl. Brian C. Catlett with voluntary manslaughter for fatally shooting 19-year-old Gary Albert Hopkins Jr. outside a Lanham Hills fire station.

Catlett was in his police uniform, moonlighting as a security officer at a dance when a fracas broke out. Catlett called for backup, and Officer Devin C. White used his cruiser to prevent a car from leaving the fire station's parking lot, according to testimony.

White jumped out with his gun drawn but allowed a young man to exit the car and walk away, witnesses testified. Then, Gary Hopkins climbed out a passenger window.

Witnesses disagreed about what happened next. Some said Hopkins tried to grab the police officer's gun and struggled with him. Others said they saw White point his gun at Hopkins and Hopkins push it away; some said Hopkins had his hands in the air. What is not in dispute is that Catlett fatally shot Hopkins in the chest.

In acquitting Catlett, Circuit Court Judge E. Allen Shepherd cited DNA evidence suggesting that White's gun had been touched by the victim, which "directly contradicted" prosecution witnesses.

Johnson, however, had not presented the DNA evidence to the grand jury. He said that because the gun was not tested until four months after the shooting, police could have tampered with it, though he presented no evidence of tampering.

"They made a presentation to the grand jury that was distorted and unfair," said Bonsib, who defended Catlett. He argued that Catlett would never have been indicted if the grand jury had heard about the DNA.

Officer John Rogers In September 1999, Circuit Court Judge Joseph S. Casula acquitted Greenbelt police Officer John Rogers of second-degree assault. Rogers was charged with knocking down a WRC-TV (Channel 4) cameraman at a graduation ceremony at Eleanor Roosevelt High School in Greenbelt in June 1998. The cameraman suffered a broken collarbone.

Rogers testified that he put his hand on the cameraman's arm to get his attention, but the man jerked around and fell. The officer said he also fell, landing atop the cameraman.

Again, witnesses were split on what they had seen. And Judge Casula, now retired, said in an interview that he gave credence to a deputy sheriff who testified for the defense that the cameraman tripped over his own feet. "I couldn't really say beyond a reasonable doubt that anyone pushed [the cameraman] down," Casula said.

Sgt. Christopher Clites A prosecution witness again proved unconvincing when a Circuit Court judge acquitted Riverdale Park police Sgt. Christopher Clites in January of charges of assault and using a handgun in the commission of a felony.

In that case, prosecutors had a single witness and an alleged crime with no injuries.

The witness, Ronald Fleming, testified that he was driving on Annapolis Road in the Bowie area in April 2001, when he and Clites, who was traveling on the road with a female friend, became angry with each other's driving.

The two drove to a side street. Fleming testified that Clites forced him off the road, got out of his car and brandished a gun in his face.

Clites testified that he approached Fleming with his badge in his left hand and his gun in his waistband. Circuit Court Judge Dwight D. Jackson said the sergeant's account was more believable.

Sandra Jordan, a former federal prosecutor in the western district of Pennsylvania and a professor at the University of Pittsburgh School of Law, said charging police officers with assault when there is no injury is probably an exercise in futility.

"You've got to have evidence of bodily injury," Jordan said. "A person's testimony standing by itself will probably not be enough. You need photographs, hospital records."

Officer Vincent D. Lyew In charging Mount Rainier police Officer Vincent D. Lyew with stealing cash, a cell phone, pager and jewelry from a teenager during an arrest, Johnson's prosecutors again relied on a single witness, the alleged victim, who came forward more than 18 months after the alleged theft.

In January 2000, Gregory Sobers Hewitt, then 19, was arrested during a traffic stop on charges of possession of marijuana and an alcoholic beverage. Hewitt was a passenger in the car. The charges were never pursued. But in late July 2001, Hewitt called Mount Rainier police and claimed Lyew had taken $300 and other items that had not been returned. Lyew was charged nine months later.

During the two-day trial, Assistant State's Attorney Jennifer Japp struggled to introduce evidence.

Japp repeatedly tried to ask Mount Rainier Deputy Chief Charles Williams about police training, policies, and general orders. Over and over, defense attorney Lisa L. Hardy objected, and the judge sustained 13 of 14 objections.

His patience clearly strained, Judge Thurman H. Rhodes told Japp: "Counsel, this is a theft case. I don't see how this is relevant."

When the defense attorney asked Rhodes to throw out the charges, Japp argued that, if Lyew was innocent, he should take the stand and testify.

Exasperated, Hardy looked at Rhodes and said, faintly, "Your honor -- the Constitution," referring to constitutional protections against forcing defendants to testify against themselves.

Rhodes nodded in acknowledgment. The judge quickly acquitted Lyew, noting that Hewitt testified that he did not know the number to his cell phone, did not have documentation proving he owned a pager, and had no receipts for the jewelry he said was stolen.

Officer Devin C. White Prosecutors primarily relied on a sole witness in charging county police Officer Devin C. White with assaulting a 25-year-old Lanham man, Khalil Majlaton, during a traffic stop in October 2000.

White, who was also involved in the shooting incident involving Cpl. Catlett, was indicted on two counts of second-degree assault and a count of malfeasance for allegedly breaking Majlaton's ankle.

Circuit Court Judge Sherrie L. Krauser threw out the assault charges because the indictment was obtained after the one-year statute of limitations had expired. She allowed the charge of malfeasance, a misdemeanor with a two-year statute of limitations.

The day the trial began, Majlaton in an interview accused Johnson's office of deliberately botching the prosecution by coming to court unprepared. Majlaton said prosecutor Roland Patterson had asked him a day or two before the trial to collect court files and round up prosecution witnesses.

Johnson defended Patterson at the time, prompting the judge to question Johnson's grasp of criminal law.

In his opening statement, Patterson said White threw Majlaton to the ground while standing on his foot, fracturing the young man's ankle.

But Majlaton, Patterson's key witness, gave a different account, testifying that the officer had thrown him to the ground, then lifted Majlaton's leg in the air and twisted his ankle, causing the break.

The defense did not call any witnesses. The judge acquitted White and noted that the indictment was defective because it did not describe a crime.

Cpl. Joseph C. Partenza

And Cpl. Mark Elie Johnson has often spoken of how difficult it is to break the "blue wall of silence," but in two cases, he has had county police officers as his key witnesses. In both cases, the officers who testified for the state provided testimony that ultimately helped the defense.

Last March, Johnson indicted county police Cpl. Joseph C. Partenza and Cpl. Mark Elie, on charges that they assaulted a burglary suspect inside the garage of a Chillum gas station in January.

The charges were sparked by Cpl. Joseph Diaz, who reported to supervisors that he believed the suspect, Hector Millan, was bitten by a police dog and beaten without justification.

In the week leading up to the trial, defense attorneys prepped the two officers with mock direct examinations and mock cross-examinations. In contrast, prosecutors didn't talk to Diaz or Millan between the indictment and the trial three months later.

Under cross-examination by Elie's attorney, Timothy F. Maloney, Millan testified that he was bitten by the dog just once, not twice, as prosecutors asserted. Diaz testified that he never saw Partenza do anything improper. In early August, Circuit Court Judge Shepherd acquitted both officers of second-degree assault.

Overturned on Appeal Johnson came closest to obtaining convictions in a police misconduct case in May 1995, when District Court Judge Frank Kratovil found three officers guilty of beating burglary suspect Henry L. Gray. Gray had suffered a broken clavicle and other injuries after he was caught trying to escape from a Suitland pizza shop he had broken into in October 1994.

The officers got an automatic appeal for a Circuit Court trial, where they were tried with a fourth officer. In the Circuit Court trial, which took place before a jury, a defense medical expert testified that Gray would have suffered much more severe injuries if he had been attacked as the key prosecution witness, Officer Kenneth Garland, described. Garland testified that the defendants "whaled" on Gray's face and torso with their slapsticks. A jury acquitted each of the officers.

"If what Garland said had occurred, Gray would have had no face left," said David M. Simpson, who defended one of the officers.

Retired Judge Casula, who presided over the trial, said he was skeptical of Garland's testimony. Referring to an alleged face kick, which Garland demonstrated in court, Casula said: "Gray would have broken his neck or something. I think [Garland] embellished."

"The citizens know my reputation. They have spoken about the fact they have confidence in me," prosecutor Jack B. Johnson said in a voice mail message.