The Temple physics professor whose life was turned upside down when the U.S. government filed and later withdrew espionage charges against him has been notified that the government will not refile the charges.

"The U.S. Attorney's Office has notified Professor [Xiaoxing] Xi's defense team that there will be no new charges and that the government will return his seized property," said Michael A. Schwartz, one of Xi's lawyers.

Whether the government might recharge Xi had been an open question since September, when prosecutors withdrew the existing charges "without prejudice," meaning that they could be revived.

Federal prosecutors had declined comment on their intentions when they withdrew the charges.

Xi, a naturalized U.S. citizen of Chinese descent, is an expert in superconductor research. He was charged last May with wire fraud, allegedly involving the transfer of sensitive U.S. defense technology to entities in China, a charge he vigorously denied.

Xi had contended that the U.S. Attorney's Office and the FBI misunderstood the science that the case was based on. Prosecutors backed down when shown their mistakes.

Xi, who is back at Temple, has talked publicly about the devastating impact on his life and family. Another Temple professor established a legal defense fund in his name. The site - - says that Xi's legal fees exceeded $220,500 by August and that $29,100 had been raised.

Reached via email, Xi declined comment.

Xi's Washington-based defense lawyer, Peter Zeidenberg, said the federal government's prosecution had "been awful" for his client.

"It's like getting diagnosed with a terrible illness," Zeidenberg said.

Since charges were dismissed, he said, the government's response has been "not even 'sorry.' It's 'no comment.' "