A retired machinist who unquestionably helped kill hundreds of Jews at the Treblinka concentration camp was stripped of his U.S. citizenship yesterday by a federal judge. Bronislaw Hajda, who is 73 years old, lied to cover up his Nazi past when he came to the country nearly half a century ago, listing his occupation as a shoemaker, this according to U.S. District Judge David Coar, who said this in his ruling. The government said it will now seek to have Hajda deported.