MAALOT-TARSHIHA, Israel -- Franz Feibel spent five years in the Buchenwald concentration camp, helplessly watching the ashes of Jewish prisoners spew out of the crematorium smokestack.
Today, at age 93 and in a nursing home, he is cared for by Oliver Raag, a German geriatric nurse whose grandfather transported disabled Jews and other Germans to a gas chamber.
Raag is one of more than 100 Germans doing volunteer work in Israel at any given time to atone for the deeds of their parents and grandparents.
''The more I learned about that period in German history, the more I wanted to come here to show that there are other Germans who are not like the Nazis," said Raag, 30.
The relationship between the Germans and the elderly Israelis is often ambivalent. Some of the survivors still can't bear to hear German spoken, while others say their idealistic young caregivers are a comfort.
The ties between Israel and Germany are also complex.
Germany is one of Israel's most vocal defenders in the European Union and a leading trade partner. Since the 1950s, Germany has paid some $80 billion in reparations to Holocaust survivors worldwide, including some 250,000 living in Israel today.
Some younger Israelis dreaming of settling in Europe are urging parents and grandparents to reclaim their German citizenship, while some older ones still refuse to visit Germany or buy any of its products.
''So long as there are Holocaust survivors alive and so long as the Holocaust is part of the biography of many Israelis and many Germans, it will be a part of concrete history," said Tom Segev, an Israeli historian.
The biggest German volunteer group, Action Reconciliation Service for Peace, has been in Israel since 1961. Currently, 25 of its volunteers are here.
Another group is Tzedaka, a faith-based foundation funded by German Christians seeking to help heal the wounds inflicted by the Nazis. Tzedaka's projects include Beit Eliezer, a 24-bed nursing home for Holocaust survivors in northern Israel, and an inn in Shavei Tzion where survivors can have free 10-day vacations.
At Beit Eliezer, 40 volunteers cook and clean, as well as feed and bathe the patients. An Israeli doctor and a social worker have paid positions. About two-thirds of the annual $477,000 budget comes from private donors in Germany, and the rest from patient contributions.
Raag was haunted for years by his grandfather's role in transporting disabled Jews and other people to a gas chamber operation in Germany's Grafeneck Castle, which specialized in killing mentally and physically handicapped people.
He said he began to overcome the guilt after researching his family history and discovering that his grandfather's job was forced on him by the Nazi government and nearly caused him a nervous breakdown.
He said his volunteer work is ''not really to make up for it, but rather to try to help heal the wounds, which helps me deal with the guilt."
Feibel has been a patient at Beit Eliezer for 12 years.
At Buchenwald, he recalls, he was beaten so often that he begged his Nazi captors to kill him. At the end of World War II, he was forced into a 130-mile death march from the camp near Weimar in Germany to Theresienstadt, near Prague.
''We walked in the night and in the day. We had few clothes and it was snowing. Anyone who couldn't walk was shot," he said.
Pictures of friends, his dead siblings, and one surviving relative hang over his bed.
''These are different Germans . . . This is something else," Feibel said, while he and Micha Beyer bantered in a mixture of Hebrew, German, and Yiddish.
They were joking about whether Beyer, a Christian, would say the Jewish prayer during the Sabbath meal on Friday night, the one evening a week when staff and patients eat dinner together.
Before coming here for about one year, every volunteer attends a monthlong seminar on the Holocaust. Some, like 20-year-old Immanuel Wirth, choose service in Israel in lieu of conscription into the German military.
''The Holocaust is part of our history in Germany, so I wanted to know the people who survived the Holocaust and see how they feel," said Wirth, of Stuttgart, who has spent a year at Beit Eliezer.
Lachs Etelka, 77, an Auschwitz survivor, has a blue death-camp tattoo -- A-16067 -- burned into her left arm, and is still haunted by memories, for instance of trying to drink urine to quench an impossible thirst.
''I still see pictures in my head and I wake up at night," she said.
During her first day at the Tzedaka inn, she was stunned to be welcomed so warmly by Germans.
''The way they greeted me -- I have no words. In every sea there are many types of fish," Etelka said.