A Temple University physicist charged with scheming to help Chinese organizations obtain technology from a U.S. company pleaded not guilty in a federal court in Philadelphia yesterday.

Xiaoxing Xi, 57 years old and a former chair of Temple’s physics department, is well known for his contributions to the development of thin-film materials and in 2007 was elected as a fellow of the American Physical Society for “his extensive and seminal contributions” to the field. In an indictment unsealed on 21 May, the U.S. Attorney’s Office for the Eastern District of Pennsylvania charged Xi with four counts of wire fraud with the intent to assist unnamed entities in China to become leaders in superconducting thin-film technology.

In an e-mail to Science, Xi’s lawyer, Peter Zeidenberg, a partner in the Washington, D.C., firm Arent Fox, wrote, “Professor Xi is innocent of these charges.” No trial date has been set yet.

The charges against Xi are the latest in a string of allegations brought by the Justice Department against Chinese researchers working in the United States or in China. Earlier in May, the department charged six Chinese with stealing chip technology from two U.S. companies. One of the men, Zhang Hao, an engineering professor at Tianjin University, was arrested on 16 May when he landed at Los Angeles International Airport on his way to a conference. Tianjin University has called on its faculty, students, and alumni to donate money to aid Zhang’s legal defense.

The Obama administration’s stepped-up campaign against perceived Chinese economic espionage has had setbacks. For instance, an eight-count indictment including charges of “commercial bribery conspiracy” brought in May 2013 against former New York University professor Yudong Zhu and two others for alleged attempts to send MRI technology to China resulted in a single guilty plea by Zhu last March to a lesser charge of making a false statement on conflict-of-interest forms for a National Institutes of Health grant. Also in March, just a week before a trial was to begin, prosecutors dropped all charges against Chinese-American hydrologist Sherry Chen, who had been accused of espionage last year. Members of Congress have called for a review of the case to see whether Chen’s race played a role in the accusations.

The indictment against Xi details activities that seem commonplace to people familiar with the interactions between overseas Chinese scientists and their native land. It states, for example, that Xi served as a referee for China’s high-technology development program, the so-called 863 Program. But many Chinese scientists in the United States serve as reviewers in Chinese government-administered grant programs. Zeidenberg, who successfully defended Chen, wrote that Xi “fully expects that justice will be done and he will be exonerated.”