Somewhere after forsaking his religion and joining the banned Nazi party, police officer Franz Stangl crossed the line--commanding a killing squad in the name of the fatherland.

Yet when exactly did Stangl go from good cop to very, very bad one? Where is the line? Who decides? At the end of a disturbing trek through history at the U.S. Holocaust Memorial Museum last week, 24 D.C. police recruits read Stangl's talk and tried to fathom his walk.

If an ordinary police officer in the Nazi-era could cross the line and do what Stangl did, could they? At times, pricked by fear or desire, an officer can fall prey to doing wrong in the name of career advancement or an effort to blend in. The fuse might be lighted by hard times at home or by meanness on the city streets.

Recruit John Carruthers, turning Germany's horror over in his mind, could hardly fathom the possibilities.

"It almost seems the people were brainwashed--the police," Carruthers said in a give-and-take with museum educators. "It seemed like they were almost stepping out of their own bodies and doing this stuff."

But to recruit Dana Armstrong, a slip into the dark side seemed less far-fetched. She could imagine a beginning in the common echoes of squad-room complaints. Police say, " 'They won't give us the right equipment' or, 'We're not getting paid.' This is, maybe, to show us what can happen if we get into that way of thinking."

For recruit class 99-2, exploring the Holocaust is part of a novel exercise inspired by D.C. Police Chief Charles H. Ramsey, who visited the museum and saw the germ of a lesson on how police must ever protect individual rights.

A half-dozen D.C. police classes and the entire D.C. police command have moved through the evolving program. The department's veterans are to follow, Ramsey said, and Montgomery County police trainers are now inspecting the program.

"It opens the door to a healthy dialogue that police need to have about why they do what they do," Ramsey said. "It started in Nazi Germany with not allowing people to sit at the same bus stop and pulling people from the schools. It started with something that was very small and people said, 'That's bad, but it's nothing to get upset about.'

"Some officers unfortunately see the Constitution as something that gets in their way," Ramsey continued. "If criminals get a little smarter, then maybe we need to get smarter along with them. Suspending rights is not the way."

David C. Friedman, director of the Anti-Defamation League's regional office, invited Ramsey on a guided tour in June 1998, shortly after the police chief took command. Ramsey took the tour with other D.C. police officers and described himself months later as "totally overwhelmed."

Something disturbed him that he couldn't quite identify. He returned alone on a Saturday to investigate.

"I was so moved by it that I frankly didn't know what to think," Ramsey recalled. "When I walked through the second time and looked at the photos, I saw not only Nazi soldiers, I saw police officers participating. Germany was a democratic country, but there had been a gradual breakdown in civil rights for Jews.

"I saw for the first time how important it is that we as police officers are defenders of the Constitution. That might seem simple, but a lot of times, that gets lost," Ramsey said. "The unspeakable can happen."

When Ramsey and Friedman later discussed a training session at the museum, plans were fluid, but the mission was real. Six months later, in January, workshops for police were underway on themes both vast and universal: the collapse of moral authority, the loss of individuals to stereotypes, the breakdown of systems, the failure of reason.

When the recruits enter the museum during several days of sensitivity training, the day starts with a two-hour tour of the Nazi era, from the ruins of the Weimar Republic to the rise of Adolf Hitler to the massacre of millions in the name of ethnic purity.

Film of Nazi rallies in Berlin leads to scenes from book-burnings and the boycott of Jewish-owned shops. Then comes the destruction of synagogues on Kristallnacht, Nov. 9, 1938. Germany invaded Poland less than one year later.

Arthur Brown, a native Washingtonian leading one group of recruits, pointed to a floor-to-ceiling photograph of a destroyed synagogue in Essen. He told his listeners, "This is hate."

Elsewhere on the tour, Brown drew attention to a photo of a German police officer in a long coat with a fierce-looking dog. He also pointed to one scene at the end of the war, where Dwight D. Eisenhower, then a commanding general, later a president, said after the concentration camps had been liberated, "The things I saw beggar description."

Live bodies as thin as scarecrows. Dead bodies stacked and burned like firewood. Camp survivors who spilled stories of incomprehensible privation and horror. Innocents slaughtered. Innocence forever undone.

"The Nazis couldn't carry out this madness themselves," Brown said to an observer as the recruits watched film clips of naked innocents being machine-gunned. His goal is to inspire recruits to "think for themselves. That even if you see something that is evil, you as an individual can make a difference and not participate."

In a classroom, museum educator Lynn Williams asked the recruits and three Montgomery County trainers to list their obligations as police officers. Among their responses were maintaining order, enforcing the law, serving people and protecting society.

But which people? A discussion of the misdeeds of German officer Stangl and his comrades revealed that he believed he was doing what he should. That he was, in his own mind, a good cop who followed orders, even followed the law. He climbed quickly through the ranks.

"Some of us want to move up in the department," recruit Justin Branson said to the assembled group. "I don't know that if you had a tough sergeant . . . and if [the] sergeant . . . told us to do something, I don't know that all of us would have the balls to tell him no.

Lt. Bill O'Toole, director of training on the Montgomery County police force, worked his way through the museum and tried to see the connections, the details that make a distant horror meaningful in a different time and place. As it happened, he saw them everywhere.

"It didn't take much to trigger things," O'Toole said during the group discussion. "All the little subtleties turned into one big atrocity and nobody did a thing about it. We've got a lot of little subtleties in our society."

CAPTION: Police recruit Mario Todd contemplates pictures at the Holocaust Museum during a tour that is designed to teach trainees the need for tolerance in a democratic society.

CAPTION: Jay Higdon, center, and other recruits contemplate pictures from the Shtetl of Eishishok, near Vilna, in what is now Lithuania. "It opens the door to a healthy dialogue," said Police Chief Charles H. Ramsey about the visit to the Holocaust Museum.