Members of Congress and Asian communities on Thursday called on the US attorney general to investigate whether race was a factor in espionage charges against a Chinese American federal employee that were eventually dropped.

"What the case of Sherry Chen may uncover is a larger issue within the Department of Justice," said Congresswoman Judy Chu, a Democrat of California, at a press conference.

"We want ensure that Chinese Americans, like Sherry Chen, are not unjustly and prejudicially targeted," said Chu, the chairwoman of the Congressional Asian-Pacific American Caucus (CAPAC). "Thus, we ask the attorney general to review her agency's policies to determine whether race is unjustly and unfairly used as a factor in economic espionage cases."

Congressman Ted Lieu, also a Democrat of California, said that the Chen case is "another example of our federal government holding certain citizens as more suspicious because of their race and nation origins."

As members of the CAPAC, Lieu said that they want to make sure that no Federal employees would be investigated "simply because of their race and nation origins," because that is "unconstitutional violation of civil rights."

A letter signed by 22 members of the House of Representatives, including Lieu, Chu, Mike Honda, a Democrat of California, and Grace Meng, a Democrat of New York, was sent to the Attorney General Loretta E. Lynch on Thursday, restating that "no federal employee should be viewed as more suspicious because of the individual's race. Not only would such targeting be unconstitutional, it has led to shameful chapters in our nation's history."

Leaders of Asian-Pacific American communities joined the members of Congress to urge the government to carry out an investigation and share the results "no later than 120 days" from the date of the letter to Lynch.

Sherry Chen, who was born in China and is a naturalized American citizen, previously worked for the National Weather Service as a hydrologist in Wilmington, Ohio. In October 2014, she was arrested at her workplace and accused of being a Chinese spy. The government alleged that Chen used a stolen password to get access to information about the nation's dams, and gave it to a high-ranking Chinese official in Beijing.

In March, just a week before she was scheduled to go on trial, prosecutors dropped all charges against Chen without explanation, only saying that they are "exercising our prosecutorial discretion."

"Whether the arrest itself was appropriate remains a question," said Peter R. Zeidenberg, Chen's lawyer. He thought if Chen had been a white person, she might not be treated like she had been.

While Chen was released, other allegations have been made against Asian Americans or Chinese nationals in the United States over the last few years. The latest being charges filed on Tuesday against six Chinese nationals, accusing them of economic espionage by stealing mobile phone technology from two US companies.

"They came across a person of Chinese descent and a little bit of evidence that they may have been trying to benefit the Chinese government, but it's clear there was a little bit of Red Scare and racism involved," Peter J. Toren, a former federal prosecutor who specializes in computer crimes and industrial espionage, told the New York Times.

Jeremy S. Wu, the Washington region co-chair of the Committee of 100 (C-100), a Chinese-American advocacy group formed in 1990 to promote relations between the United States and China, told China Daily, "We want the Department of Justice to give a reasonable explanation on this case."

"We request the Department of Commerce to reinstate Chen to her position and compensate her loss pain and benefitsalso ask the attorney general to investigate the potential inappropriate use of law in this case," said Wu.

Chen has had her benefits and pay restored, but she is still awaiting a decision from the Commerce Department, which oversees the weather service, on whether she will be reinstated.

Haipei Shue, president of the National Council of Chinese Americans, asked the US government and American society not to violate the interests and rights of Chinese Americans and Chinese nationals in the US when the government targets people for surveillance.

Liu Xiaoxian in Washington contributed to this story.