Mr. Swanson arrived at the commission’s office of compliance inspections and examinations in 1996 after clerking for a federal appeals court judge in South Carolina. A native of Minneapolis, he graduated from the University of Minnesota and the Hamline University School of Law. In 1999 and 2004, he played a peripheral role in examinations of the Madoff firm, current and former officials said. In the later examination, his work was reassigned to another lawyer who, after a promotion, was looking to expand his workload. From 2002 to 2005, Mr. Swanson was involved in developing a case against the National Stock Exchange. At the time, Peter Madoff was a director and Madoff Securities was a significant investor in the company. In April 2006, he became romantically involved with Shana D. Madoff while he was visiting New York. On Dec. 8 2006, her birthday, he proposed to her. They were married soon afterward and he had an opportunity to meet many of the members of his new family. The scandal has taken more than a personal toll on Mr. Swanson and his wife. Ms. Madoff has told friends that she has lost a substantial portion of her assets, which she invested with her uncle, and now teaches yoga.