JERUSALEM — In the Ukrainian town of Berdichev, Jewish women were forced to swim across a wide river until they drowned. In Telsiai, Lithuania, children were thrown alive into pits filled with their murdered parents. In Liozno, Belarus, Jews were herded into a locked barn where many froze to death.

Holocaust deniers aside, the world is not ignorant of the systematic Nazi slaughter of some six million Jews in World War II. People know of Auschwitz and Bergen-Belsen; many have heard of the tens of thousands shot dead in the Ukrainian ravine of Babi Yar. But little has been known about the hundreds, perhaps thousands, of smaller killing fields across the former Soviet Union where some 1.5 million Jews met their deaths.

That is now changing. Over the past few years, the Yad Vashem Holocaust museum and research center in Israel has been investigating those sites, comparing Soviet, German, local and Jewish accounts, crosschecking numbers and methods. The work, gathered under the title “The Untold Stories,” is far from over. But to honor Holocaust Remembrance Day, which starts Monday evening, the research is being made public on the institution’s Web site [http://www1.yadvashem.org/untoldstories/homepage.html]