Feeling besieged by China’s spies, who have had success in stealing government and corporate trade secrets, the United States has ramped up its efforts to find moles. In at least two recent cases, however, F.B.I. agents and federal prosecutors appear to have acted with reckless haste.

On Friday, prosecutors dropped wire fraud charges filed in May against Xi Xiaoxing, the chairman of Temple University’s physics department. He was accused of sharing privileged technology with China and faced up to 80 years in prison.

Prosecutors said Dr. Xi provided the design of an item known as a pocket heater, used in superconductor research. The allegation fell apart after defense lawyers pointed out that the government had grossly misread the evidence it used to secure an indictment. As it turned out, Dr. Xi, a naturalized American citizen, had emailed scientists in China information unrelated to the pocket heater.

Xi Xiaoxing CreditMark Makela for The New York Times

The embarrassing blunder came a few months after federal prosecutors in Ohiodropped charges against another Chinese-American professional, Sherry Chen, a National Weather Service employee who was also suspected of being a Chinese mole. She was charged with four felonies, including unlawfully downloading information about critical infrastructure. Her problems began after a colleague reported that she had emailed an official at China’s Ministry of Water Resources. The colleague had been copied on the email and found it suspicious.

The email was Ms. Chen’s response to a question from a Chinese official who had asked her during a meeting in Beijing how water infrastructure projects in America were funded. The information she gave him was harmless and publicly available.

China was reportedly behind a huge breach of the servers of the Office of Personnel Management, which could well give Beijing valuable information about millions of Americans who have been granted security clearances. Further, the theft of proprietary technology poses a considerable threat to the American economy. It is hardly surprising that the Justice Department has given priority to prosecuting espionage cases involving China.

But these concerns cannot justify prosecutions driven by supposition rather than solid evidence. The charges filed against Mr. Xi and Ms. Chen traumatized them and their families and needlessly damaged their professional reputations. Nether got an explanation or an apology from the government. They deserve both.（source：New York Times）