KNOXVILLE (AP) — A federal judge declared a mistrial Wednesday in the case of a former University of Tennessee researcher charged with hiding his relationship with a Chinese university while receiving research grants from the federal government.

U.S. District Judge Thomas Varlan's ruling came after jurors notified the judge they were at an "impasse," WBIR-TV reported.

It was not immediately clear whether the government would try to prosecute Anming Hu again.

A defense motion to throw the case out is pending before Varlan. Defense attorney Phil Lomonaco had attacked the case as flimsy, misguided and political.

Deliberations began Monday, and jurors took Tuesday off before continuing Wednesday. They sent a note to Varlan Wednesday afternoon after they were unable to reach a verdict.

Hu, an associate professor in the university's Department of Mechanical, Aerospace and Biomedical Engineering, was charged in February 2020 with three counts of wire fraud and three counts of making false statements.

The charges are part of a broader Justice Department crackdown against university researchers who conceal their ties to Chinese institutions, with a Harvard chemistry professor arrested in the past on similar charges. Federal officials also have asserted that Beijing is intent on stealing intellectual property from America's colleges and universities, and have actively been warning schools to be on alert for espionage attempts.

Prosecutors say Hu defrauded the National Aeronautics and Space Administration by failing to disclose that he was also a professor at the Beijing University of Technology in China. Under federal law, NASA cannot fund or give grant money to Chinese-owned companies or universities.

"He intentionally hid his ties to China to further his career," Assistant U.S. Attorney Casey Arrowood told jurors on Monday. "This case, ladies and gentlemen, is just that simple."

Testimony has shown university officials told faculty that the NASA restriction didn't apply to them.

Lomonaco said Hu didn't think he needed to list his part-time summer job on a disclosure form and no one at UT ever told him otherwise. Hu's affiliation with the Beijing University of Technology was clearly listed in other documents, Lomonaco said. He also noted that it was NASA that sought Hu's technology.

"They wanted him to work on this project," Lomonaco said. "(A NASA contractor) sought him out because he was so qualified. (Hu) wasn't trying to trick NASA."