Following up on a recent post, U.S. v. Pu presents another instance of a trade secret theft case with an international component that the federal authorities have decided to prosecute. Yihao Pu, a former quantitative financial engineer for Citadel LLC, was arrested last Wednesday for allegedly stealing proprietary information related to the Chicago-based company’s trading system as part of a plan to launch his own hedge fund in China. After filing its own civil suit against Pu on August 29, 2011 and obtaining a temporary restraining order, Citadel brought the matter to the federal authorities. In this instance, the company chose both to take rapid action on its own to protect its trade secrets as well as to refer the matter to federal law enforcement authorities. The civil case is Citadel LLC v. Yihao Ben Pu, 11CH30493, Cook County, Illinois and the federal case is U.S. v. Pu in the Northern District of Illinois.