According to Chilean governmental reports, Weisfeiler was hiking near the border of the Colonia Dignidad at the time of his disappearance. Various actual or supposed eyewitnesses' conflicting reports make the details of the disappearance impossible to discern. The Chilean government has ruled that Weisfeiler had entered the confluence of two swift-moving rivers and drowned, his body never to be recovered. Local fishermen say they camped with Boris and gave him directions northward, toward a bridge near the Colonia. Some people claim to have seen his footprints near the river and to have found his backpack and other items (the items may have been sold or destroyed by the Chilean government in the late 1990s, as evidenced by Chilean governmental documents and published news articles).