The United States Commission on Civil Rights has sent a letter to the US attorney general arguing that the government may be "failing to exercise sufficient due diligence" in criminal investigations involving Chinese Americans.

The USCCR, a bipartisan, independent commission of the federal government, issued a press release on Monday to reinforce the Nov 18 letter sent to Attorney General Loretta Lynch regarding high-profile prosecutions of two Chinese-American scientists.

Sherry Chen, a hydrologist with the US National Weather Service in Ohio, and Xiaoxing Xi, former chair of the Physics Department at Temple University in Philadelphia, were accused of economic espionage. Charges against both were subsequently dropped.

Chen, a naturalized US citizen, was accused of downloading information about dams in the United States and lying about meeting with a Chinese official. The charges were dismissed in March. After the incident, 22 members of Congress sent a letter to the Justice Department on May 21.

"What I don't understand the most is why my agency hasn't given back my job yet," Chen said at a Nov 17 press conference. "I lost my job, which is the only financial source for me to survive."

Xi was arrested on charges of sharing confidential schematics of laboratory equipment with scientists in China. FBI agents raided his home and handcuffed him in front of his wife and children. The charges against Xi, also a naturalized American citizen, were dropped in September after scientists, including the co-inventor of the equipment, told the government that the blueprints were not for the equipment.

"Yes, I have collaboration with my Chinese colleagues, but so do other non-Chinese scientists," Xi said at the Nov 17 press conference. "Is it because of my ethnicity that I'm more suspicious than other scientists? FBI should have called me and asked me what I was doing, and how I did my research. That is how they usually conduct an investigation for the white-collar cases, but they did not."

"While combating spying and economic espionage is vital to our national security, just as important are the protections of our civil rights and civil liberties," Commission Chairman Martin R. Castro, on behalf of a majority of the commission, said in the release. "American citizens are entitled to due process and should not be targeted on the basis of their race or ethnicity — that is un-American."