A Scientist Without a Country

This article was co-published with ProPublica.

On September 9, 1999, David Letterman entertained millions of television viewers by riffing on a scientific breakthrough that had made an obscure Princeton assistant professor famous overnight. The late-night host’s top-10 list of “Term Paper Topics Written by Genius Mice” — including “A Sociological Study of Why Cats Suck” and “Outsmarting the Mousetrap: Just Take the Cheese Off Really, Really Fast” — saluted Joe Z. Tsien’s achievement in genetically engineering a mouse to learn faster and adapt better to changing conditions.

As the years passed, Tsien’s fame faded. Then, like hundreds of other scientists at U.S. universities, he found himself in the crosshairs of a federal crackdown on China’s theft of American research and expertise.