WASHINGTON - Alongside the atrocities were the people who should have stopped them.

The images of the police who participated in the crimes of Nazi Germany, frozen in time at the U.S. Holocaust Memorial Museum, haunted Charles H. Ramsey when he first visited nearly two decades ago as chief of Washington police.

On Tuesday, Ramsey sent 75 Philadelphia police recruits to see the same images. Now Philadelphia police commissioner, he wanted the trainees to learn about guarding the rights promised by the Constitution, about the sacred relationship with the people they will protect, and about how disastrous the results can be when police lose sight of those priorities.

"To find a way that you can illustrate what values mean, and what the absence of those values mean, in as concrete a form as the museum, is a very powerful thing," said David Friedman, the regional director of the Anti-Defamation League, who spoke to the Philadelphia recruits.

The recruits Tuesday joined more than 90,000 members of police agencies who have been through an ethics training program Ramsey conceived after his first visits to the museum in the 1990s, and that has since spread to all levels of law enforcement, including the FBI and Secret Service.

Wearing tan uniforms with epaulets and precisely rolled sleeves, the cadets for the Philadelphia and Temple University Police Departments silently craned their necks as they viewed photos of Holocaust victims that covered museum walls four stories high.

"That made an impression," said Breciendi Burgos, 28.

They walked past a collection of shoes recovered from the Majdanek concentration camp in Poland.

They listened as their guide, Florence Bank, told the story of a friend who had survived the Holocaust - but never knew the fate of her family until late in life. That's when she learned that her father and brother had switched lines at Auschwitz so that her mother and sister would not go to the gas chambers alone.

Bank fought back tears as she told the story. Her friend has since died.

"Who's going to tell their stories?" Bank asked the recruits. "It's up to you."

Her listeners, mostly in their 20s, said the photos and films brought to life what they had only read about in textbooks. They were transfixed by images of the dead, many of them left naked in ditches.

"You couldn't believe how many," said Chris Rycek, 23. "You don't think it's that much until you saw the pictures."

In 1998, Ramsey first visited the museum with Friedman - and left "overwhelmed with emotion," as he wrote in a June paper for Harvard's Kennedy School of Government and the National Institute of Justice.

On a second visit, alone, Ramsey wrote that he noticed the pictures of police, and began to understand their role.

"Where were the police when libraries were being looted and books burned?" he wrote.

On his initiative, the museum and the league began a training program for Washington police in 1999. It spread by word of mouth to other federal, state, and local agencies. Now, Friedman said, every new FBI agent goes through the training.

Throughout, the presenters stress how police in Germany lost sight of their "core values."

"It all focuses on their relationship to the people they serve," Friedman said. "That's what gives their job meaning, but it's the essence of what differentiates policing in a constitutional democracy from other countries."

Sarah Campbell, a program coordinator for the museum, pointed out that German police had taken oaths much like American police do, but failed to uphold them.

"What makes you different?" she asked as the program began. "That difference makes all the difference."

The Philadelphia department has been sending recruits since Ramsey became commissioner in 2008. This visit came close on the heels of Thursday's indictments of six narcotics officers on corruption charges.

"One of the good things that comes out of bad is that it's a timely incident, that we can use to stress upon [cadets] what the effects are of someone who tarnishes the badge," said Chief Inspector Tony Boyle, who leads the department's training bureau. "It's not an abstract thing for them that happened in the past."

The recruits, he said, have asked instructors about the corruption case.

"It's tangible to them," Boyle said.

Learning more about the Holocaust has its own value, he said, and so does learning more about the dangers of abuses of power.

"What we never talked about in history class is the role that police had in the Holocaust," said one recruit, Antonio Bennett, 25, of South Philadelphia. "If maybe they would have stepped up their presence and remembered their constitutional rights, maybe they could have protected some people."

The museum's message for law enforcement officers took time to hone, especially in the program's early days, when civilians tried to lecture police, said Lynn Williams, the museum's director of leadership programs.

"We struggled with a very honest, honest audience," she said. "Goodness, they'd tell you when it was no good."

The program gained traction by focusing on how ordinary people in Germany, including the police, slowly came to be complicit in one of history's great horrors.

"These were not handpicked killers. They started out like regular people - like you," Friedman told the recruits.

Nazis used the police's "special relationship" with their communities to give themselves and their actions legitimacy, Williams said in an interview.

"It really teaches us that democracy is very fragile," she said. "Small breakdowns erode us greatly."

What choices did individual police officers have? They had jobs, families. What if they were pushed to violate their oath?

"Go to the FOP," one recruit answered.

The mention of the Fraternal Order of Police was a rare moment of levity in the daylong visit.

In his June essay, Ramsey wrote that "above all else," the police's role is to protect people's rights - to assemble, to speak out to criticize their government, and to be secure at home.

"We must never buy into the notion," the commissioner wrote, "that taking away individual rights is somehow the way to solve our problems. ... If our officers leave their day at the Holocaust museum with only one lesson learned, I hope it is that one."