Boris Weisfeiler is a Russian-born mathematician who lived in the United States before going missing in Chile in 1985, aged 43. The Chilean government claimed that he drowned, but his family believes he was forced to disappear near Colonia Dignidad, an enclave led by ex-Nazi Paul Schäfer.
Weisfeiler was born in the Soviet Union. He obtained his Ph.D. in 1970 from the Steklov Institute of Mathematics Leningrad Department, as a student of E. B. Vinberg. In the early 1970s Weisfeiler was asked to sign a letter against a colleague, and for his refusal was branded "anti-Soviet". Like other Russian Jews he also experienced discrimination. In 1975, Weisfeiler left the USSR in order to freely practice his career and religion. After a short time under Armand Borel at the Institute for Advanced Study near Princeton University, Weisfeiler settled in as a professor at Penn State University. In 1981, he became a naturalized citizen of the United States.
Weisfeiler's research spanned twenty years, and he published three dozen research papers. According to his colleague Alexander Lubotzky, Weisfeiler was studying "the more difficult questions" of algebraic groups in "the case when the field is not algebraically closed and the groups do not split or — even worse — are nonisotropic". He is known for the Weisfeiler-Lehman algorithm, the Kac-Weisfeiler conjectures, the Weisfeiler filtration, and work on strong approximation and on finite linear groups.
Chile was under U.S. sanctions for most of the 1970s and 1980s as a result of its non-cooperation in the Orlando Letelier murder in Washington, and was then controlled by staunch anti-communist dictator General Augusto Pinochet. Under Pinochet, Chile is alleged to have committed widespread human rights abuses. Before his death in 2006, Pinochet, by then the former head of the military government had been prosecuted for his role in Operation Colombo and indicted in absentia in other countries. As well, the democratic government of Chile took steps to investigate other activities under Pinochet's regime.
According to Chilean government reports, Weisfeiler was hiking near the border of the Colonia at the time of his disappearance. Conflicting stories of various eyewitnesses make it impossible to conclude what really happened. Officially, the Chilean government 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 north toward a bridge that happened to be in proximity of the Colonia. Some claim to have seen his footprints near the river, finding his backpack and other items. These items appear to have been sold or destroyed by the Chilean government in the late 1990s, as documented by Chilean government documents and published news articles. 
Although no conclusive proof connects the disappearance of Weisfeiler to any entity, there is one group under suspicion by both U.S. and Chilean officials. Unbeknownst to most of the outside world, a place called Colonia Dignidad sat on a large land tract close to the Argentinian border. Appearing idyllic, the enclave was run by German expatriates, some of whom were alleged to be Nazi war criminals, others believed to be Nazi sympathizers. The leader of the Colonia for most of its existence was Nazi Paul Schäfer.  The Colonia had a cult-like atmosphere, in which many children were molested, a crime for which its leaders have faced prosecution. Schafer was convicted in May 2006 in connection with the allegations of child abuse at the Colonia. It was reported by the BBC (as well as suggested in Chilean government documents ) that Chilean DINA secret police (disbanded in 1977) brought suspected anti-government prisoners there for interrogation.
According to U.S. State Department 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 has immigrated to the United States and continues to petition numerous authorities to determine his fate. In early 2006 a Joint bipartisan Congressional letter signed by 27 Senators and Congressmen was delivered to Chilean President Michele Bachelet in the hopes of speeding up the investigation into his fate. In 2010 a similar letter signed by 52 Senators and Congressmen was delivered to Chilean president Sebastián Piñera.
On August 21, 2012 a Chilean judge ordered the arrest of eight retired police and military officers in connection with the kidnapping and disappearance of Boris Weisfeiler. According to the court filings, the suspects will be prosecuted for "aggravated kidnapping" and "complicity" in the disappearance of a U.S. citizen between January 3-5, 1985.
The ruling makes no mention of where Weisfeiler might have been taken after his detention or what happened to him afterwards.
Several embassy cables published by Wikileaks (e.g. 05SANTIAGO2539, 08SANTIAGO93) mention Weisfeiler. Possibly the most interesting one is 09SANTIAGO680, which says
- "La Nacion" traveled to the exact location where he was last seen and talked to key witnesses. From these accounts the conclusion is that Weisfeiler approached the home of a farmer to ask for hot water; a police patrol and two civilians well known in the area arrived at the farmer's house asking about a foreigner; the group was later seen carrying on horseback the body of a man wrapped in a blanket. His hands and feet were visible. The general belief in the area is that Weisfeiler was detained, beaten, and his body buried and exhumed days later. His disappearance is the last human rights violation committed by the military regime, mobilizing U.S politicians, who have demanded the GOC resolve the case. In Santiago, FBI agents have increased their activities with local authorities in an effort to solve the case. "La Nacion" claims that the witness accounts in this article contain information that "has never been revealed before" (La Nacion, government-owned, editorially independent, 7/19).
In other media and popular culture
- A short film The Colony based on Weisfeiler's disappearance and directed by Steven List was released in 2007.
- Tracing a Mystery of the Missing in Chile
- The Mathematics Genealogy Project - Èrnest Vinberg
- Alexander Lubotzky (January 2004). "A Tribute to Boris Weisfeiler: The Mathematics of Boris Weisfeiler". Notices of the American Mathematical Society 51 (1). Retrieved 2006-11-21.
- "The Weisfeiler Lecture in Mathematics". Retrieved 2006-11-21.
- http://books.google.com/books?id=As7DBIxNt3oC&pg=PA77&lpg=PA77&dq=U.S.+sanctions+chile&source=bl&ots=WFpjqzWC0R&sig=ckJhFBs4nFeaXhiyZcurzE8ABcg&hl=en&ei=hzlYToXiO8rX0QG72diHDA&sa=X&oi=book_result&ct=result&resnum=2&ved=0CCEQ6AEwATgK#v=onepage&q=U.S.%20sanctions%20chile&f=false Chile
- Official website for Boris Weisfeiler
- "The Colony (II) (2007)". Internet Movie Database. Retrieved 2013-12-01.