Declassified US documents suggest a Chilean army patrol seized Weisfeiler and took him to Colonia Dignidad, a secretive Germanic agricultural commune set up in Chile in the 1960s.
After the effective end of military rule, in 1990, the Chilean government took steps to investigate additional activities under the Pinochet regime.
[7] Although no conclusive proof connects Weisfeiler's disappearance to any entity, some American and Chilean officials do suspect one particular group.
Idyllic in appearance, the Colonia was run by German expatriates who included alleged Nazi war criminals and sympathizers.
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.
On August 21, 2012, a Chilean judge ordered the arrest of eight retired police and military officers in connection with the alleged kidnapping and disappearance of Boris Weisfeiler.
The case was closed in 2016, after the judge ruled the disappearance to be a common crime (for which the statute of limitations had passed), not a violation of human rights.