According to United States Department of State reports, other witnesses claim they saw Boris Weisfeiler in the Colonia, several years after his disappearance. At least one claims he was alive some three years later; another claims he was assassinated as a Soviet or Jewish spy. Weisfeiler's whereabouts remain unknown, and his sister Olga, who, like her brother, emigrated to the United States, continues to petition numerous authorities to determine his fate. Early in 2006, a bipartisan Congressional letter signed by 27 senators and representatives was delivered to Chilean President Michelle Bachelet in the hope of speeding an official Chilean investigation into his fate.