A Republican congressional candidate whose campaign was linked to an intimidating letter sent to Hispanic voters said Tuesday he would not quit the race if he is charged with a crime.

"If you're innocent and somebody charges you, would you give up? No, you've got to fight," said Tan Nguyen, who is seeking to unseat five-term Democratic Rep. Loretta Sanchez in California's 47th Congressional District.

"Innocent people can be persecuted," he told The Associated Press.

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The state Department of Justice has opened a voting rights investigation into the letter sent to certain Democratic voters in Orange County.

The letter, written in Spanish, warned: "You are advised that if your residence in this country is illegal or you are an immigrant, voting in a federal election is a crime that could result in jail time."

Immigrants who have become naturalized U.S. citizens are eligible to vote.

Nguyen, a Vietnamese immigrant who has made illegal immigration a centerpiece of his campaign, was interviewed at his campaign office. It was open for the first time since being raided last week by investigators who seized computers, political signs and other items.

Nguyen said he purchased a database of 14,000 Hispanic voters from a Burbank company called Political Data Inc. so he could send Spanish-language fliers to voters. He said his campaign sent four fliers using the database before his office manager forwarded the names to an outside party.

Nguyen refused to identify the office manager or the third party who he said mailed the letters.

He said last week that he believed an employee in his office might have used his campaign's voter database to send the letter without his knowledge.

He reiterated that he did not authorize or approve the intimidating letter and said neither he nor any of his three paid campaign staff members wrote or funded the mailing.

"It has to be clear: I didn't authorize it, I didn't approve it, we didn't send it out from the campaign. People who are saying that it's coming from the campaign is a fat lie," he said.

William Braniff, Nguyen's campaign attorney, said a volunteer drafted an English version of the letter and e-mailed it to a volunteer who translated it into Spanish. The office manager forwarded the database of Hispanic voters to a volunteer, said Braniff, who declined to give the name of the office manager.

Nguyen called for an investigation into what sparked the criminal probe.

Nathan Barankin, spokesman for the state Department of Justice, said the letters alone triggered it.

"What prompted the probe was hundreds of letters arriving in the mailboxes of registered voters a couple weeks ago," he said.

Sanchez's campaign has said it will not comment until the investigation is complete.