The window is closing.

The mass graves aren't going anywhere, and neither is the forensic evidence - cartridges and bullets and bones. The archives are safe. But Father Patrick Desbois has but a few years to talk to people who saw the murders, and only they can identify the exact locations of the bodies and illuminate the problematic accounts in German and Soviet documents.

"We are in the small window I would say, because it's the end of the life of the witnesses, but it's also perhaps the only period in which ... they begin to feel free from the Soviet Union," Desbois said last week in a phone interview. "It's a short-term project. We think six, seven years maximum ... ."

Desbois, a Roman Catholic priest from France, has since 2004 conducted investigations into the "Holocaust by bullets" - the murder of eastern-European Jews by German soldiers during World War II. He will speak at St. Ambrose University on August 27.