"Stolpersteine" (stumbling blocks) have been laid for Karolina Cohn and her family at the site where they once lived in Frankfurt

Dozens of relatives from three continents came together to lay a brass plaque in a pavement in Frankfurt on Monday in memory of a Jewish schoolgirl who perished in the Holocaust and whose fate was revealed this year when her pendant was discovered beneath floorboards at the site of the Sobibor death camp in eastern Poland.

Karolina Cohn may have known Anne Frank, the teenage girl killed in the Holocaust whose diary, written while she was in hiding in Amsterdam, has become one of the most famous documents of the Holocaust. Both girls were born in Frankfurt in 1929, just three weeks apart.

On Nov. 11, 1941, 12-year-old Cohn was deported to the Minsk ghetto along with her parents and sister.

Nothing more was known of her fate until archaeologists excavating the Sobibor site found her pendant, inscribed with her date and place of birth and the words "mazel tov" in Hebrew. It was similar to a pendant that belonged to Frank.

The relatives laid four little brass plaques, for Karolina Cohn, her sister and their parents, in front of the Frankfurt location where the family lived before they were deported. Such plaques are known as "Stolpersteine," or stumbling stones.

"It's pretty remarkable, that this little girl brought together this broken-up, fragmented family," said Mandy Eisemann, a relative from the United States who took part in the ceremony and afterward laid pink roses on the plaques.

The story of Cohn's life and death had been all but erased by the Nazis until archaeologists last year unearthed a silver pendant engraved with her birthdate and birthplace in the grounds of the former Sobibor death camp.

With the help of Nazi deportation lists, researchers identified Cohn as the owner of the amulet. It is almost identical to one belonging to Anne Frank, though it is not clear if the two girls knew each other. Both were born in Frankfurt in 1929.

The triangle-shaped pendant was found by an Israeli-Polish archeologists' team under the ruins of a hut where the women's hair was shaved before they were led to the gas chambers.

A replica of Karolina Cohn's pendant

It is not clear if Karolina was ever taken to Sobibor or if she gave the amulet to somebody else who brought it there. All traces of Karolina disappear after she and her family were deported to the Minsk Ghetto in late 1941.

After the pendant was linked to the German girl last year, a genealogist started tracking down family members and found about 40 relatives in Israel, the U.S., Italy and Japan. Many of them had never heard about Karolina and her family, but more than two dozen accepted an invitation from the Jewish Claims Conference to meet in Germany for the ceremony and a reunion.

"It's a heart-warming emotion to meet family who were strangers to us before today," said Barry Eisemann, the father of Mandy and a first cousin of Karolina. "But it's a heart-wrenching emotion to know that Karolina and the entire family perished in the Holocaust."

Holding a replica of the pendant, Greg Schneider, the vice president of the Jewish Claims Conference reminded the more than 100 participants of the ceremony than Karolina was one of 1.5 million children who were murdered in the Holocaust.

"It's almost too painful to think about what was done to this girl," he told The Associated Press in a phone interview Sunday. "But we don't have the moral right to forget Karolina."