At the high point of their careers, the so-called "Riders" were considered the best and the brightest, veterans whom rookie police officers tried to emulate. Their specialty: bringing in reputed drug dealers in record numbers from the crime-plagued streets of West Oakland.

Now, three of the four rogue officers are on trial here for using dishonest and sometimes brutal tactics in making those arrests.

Clarence "Chuck" Mabanag, 37; Jude Siapno, 34; and Matthew Hornung, 31, are charged with a total of 26 criminal counts, including kidnapping, the beating of falsely arrested suspects, and submitting falsified police reports. A fourth officer, Francisco "Choker" Vazquez, considered the Riders' ringleader, fled before prosecutors were able to charge him. Vazquez, 45, is believed to have left the country and is being sought by the FBI.

The alleged abuses came to light after a rookie officer, just 10 days on the job and fresh out of the police academy, resigned and reported his former co-workers' activities to the police department's internal affairs division. Since that time, the rookie officer, Keith Batt, has also filed a civil lawsuit against the City of Oakland, and claimed that police department supervisors should have been aware of and able to stop the alleged renegade practices of the officers who worked the graveyard shift in West Oakland, a neighborhood notorious for drug deals. Batt is now a police officer in Pleasanton, an Oakland suburb.

The trial has been underway since September and is expected to last through next month. It has riveted this city and is the largest case of police misconduct here in decades.

Assistant District Attorney David Hollister has portrayed the Riders as a clique whose members thought they were above the law and who fed off the attention they received from other officers and their supervisors for their string of drug arrests. "These are crimes of either laziness or concealment," said Hollister, who likened the arrests to the seemingly profitable energy-trading giant Enron before its fall. "The numbers look great. But if you look behind the numbers, what you see isn't what you thought was there," he said.

The defense has sought to paint Batt, the prosecution's star witness, as a naive rookie with little understanding of the ways of an urban police department fighting a deadly drug war. "You don't send choirboys out to West Oakland to get rid of drug dealers," said defense lawyer Michael Rains, who is representing former officer Mabanag, Batt's training officer at the time of the complaints.

In addition to Batt and numerous other officers, eight alleged victims also testified regarding the abuses they said they suffered in police custody. None is the ideal witness; almost all have previous arrests and convictions, the majority for minor drug offenses.

"These men are the most vulnerable. They have prior convictions; they have served time in prison; they are on parole. They are not generally believed to be victims in a case like this," said Oakland civil rights attorney John Burris, who is representing a number of the alleged victims in a separate civil lawsuit against the officers, the police department and the city.

As part of the evidence, Hollister presented enlarged photographs of some of the alleged victims, all of whom are African American, showing their injuries. Two of the witnesses testified to being handcuffed and subsequently beaten and having had rock cocaine planted on them by officers Vazquez and Siapno.

Above left, former Oakland Police officer Keith Batt testifies in September at the trial of former officers Clarence Mabanag, Matthew Hornung and Jude Siapno, at Alameda County Superior Court in Oakland, Calif. Above right, Judge Leo Dorado, background, watches prosecutor David Hollister display a photograph of Delphine Allen, allegedly beaten by former Oakland Police officers. The officers face a combined 26 felony counts.