The Prince George's County police officer charged in federal court with releasing her police dog on an unarmed, unresisting Mexican immigrant has a pattern of improperly using the dog on minorities and threatening minorities, sometimes with racial epithets, according to court papers filed by federal prosecutors.

In a filing last week in U.S. District Court in Greenbelt, federal prosecutors detail five instances in which they said Officer Stephanie C. Mohr improperly released her police dog on unresisting people or threatened to do so. Prosecutors described a sixth incident in which Mohr manhandled a neighborhood boy who had run across her lawn. Each of Mohr's alleged victims in those cases was black, according to court papers.

In addition, the police department has twice found that Mohr, 30, made false statements to a supervisor, according to the court papers.

Despite the incidents, which resulted in at least four civil lawsuits accusing Mohr of brutality, and the fact that Mohr was flagged as a potential problem officer by the police department's early warning system, Mohr has received virtually no discipline, according to the court papers and court testimony.

Mohr was briefly suspended for the incident with the neighbor child, and she was given informal counseling and a written reprimand for threatening to release her dog on a family that was cooperating with officers who were looking for a suspect, according to the court papers. Mohr was fined $100 on a finding that she made a false statement to a supervisor, which Mohr has said she is appealing.

The incident involving her alleged threats to the family had not been disclosed previously.

As officers searched a house for a man who was wanted by authorities in California, a woman who lived in the home asked Mohr to move her barking police dog farther from her, according to court papers.

Mohr refused to move her dog, then threatened the woman that if the suspect was in the house, she would turn the animal loose to bite not only the suspect but the resident's "black ass" as well, according to the court filing.

The 25-page court summary of Mohr's alleged history of excessive force and dishonesty signals that prosecutors hope to go after Mohr much more aggressively than they did during the first trial in March, when a federal jury in Greenbelt acquitted her of conspiracy and deadlocked on a charge of deprivation of civil rights.

Assistant U.S. Attorney Steven M. Dettelbach and Alexander H. Busansky, a trial attorney in the Justice Department's civil rights section, argue to U.S. District Judge Deborah K. Chasanow in the pleading that they should be allowed to introduce evidence about the incidents in Mohr's retrial, scheduled for July 31.

Mohr's attorney, David M. Simpson, said the allegations of misconduct by Mohr were overstated. "Stephanie Mohr was a very active canine officer. She's probably going to have more incidents which will be called into question than the average patrol officer would have," Simpson said. "It comes with the territory."

Simpson said prosecutors tried to introduce evidence about many of the incidents in the earlier trial but were barred from doing so by Chasanow.

The failure of police officials to take serious disciplinary action against Mohr is emblematic of how the department often fails to deal with problem officers, said Edythe Flemings Hall, president of the Prince George's County NAACP and a member of a task force appointed by County Executive Wayne K. Curry (D) last year to review the police department.

"The task force was not able to determine there was any consistent discipline applied based on the infractions by officers," Hall said.

Mohr is accused of releasing her police dog on Ricardo G. Mendez behind a Takoma Park printing shop on Sept. 21, 1995. Prosecutors allege that while Mohr released her police dog at the direction of a senior officer, Anthony Delozier, Officer James Santos beat Mendez's companion, Jorge Herrera-Cruz, for no reason.

In the papers they filed last week, prosecutors said Santos, an unindicted co-conspirator, has admitted in sworn testimony that he beat Herrera-Cruz.

The jury acquitted Delozier of a charge of deprivation of civil rights and deadlocked on a charge of conspiracy. Mohr, 30, still faces a charge of deprivation of civil rights, and Delozier still faces a charge of conspiracy.

Jurors deadlocked on the single count against Brian Rich, a former Takoma Park police detective who later became an FBI agent, who was charged with helping to cover up the dog attack by charging the alleged victims with burglary despite a lack of evidence.

Chasanow ruled last month that the government did not have sufficient evidence to retry Rich and dismissed the charge against him.

The court papers detail four civil lawsuits filed against Mohr, who was a member of the canine squad until she transferred more than two years ago. Each of the lawsuits has been previously reported in The Washington Post.

Two of the lawsuits ended with county attorneys agreeing to pay settlements. One lawsuit went to trial, and Mohr was found not liable. The fourth is scheduled to be tried in Prince George's Circuit Court in two weeks.

In that case, Jason Tyree alleges that he was in an office building to use a bathroom when police chased him. Tyree alleges he ran but then surrendered and lay on the ground, at which point Mohr used a racial epithet against him while releasing her police dog and ordering it to attack him.

Prince George's County police officer Stephanie C. Mohr is to be retried on a civil rights charge.