Ms. Napolitano said in the interview that she would not call off immigration raids entirely as some Hispanic lawmakers have suggested. “We will continue to enforce the law and to look for effective ways to do it,” she said. “That’s my job.”

Ms. Napolitano, who as governor of Arizona sparred with Republican legislators seeking tougher steps against illegal immigration, said she was looking for ways to make enforcement programs inherited from President George W. Bush less heavy-handed. She also wants to put the enforcement focus on illegal-immigrant gang members and convicts and on employers who routinely hire illegal immigrants so as to exploit them.

Immigration authorities have started audits of employees’ hiring documents at more than 600 businesses nationwide. If an employer shows a pattern of hiring immigrants whose documents cannot be verified, a criminal investigation could follow, Ms. Napolitano said.

She has also expanded a federal program, known as E-Verify, that allows employers to verify electronically the identity information of new hires. Immigrant and business groups have sued to try to stop the program, saying the databases it relies on are riddled with inaccuracies that could lead to American citizens’ being denied jobs.

But officials of the Homeland Security Department say technological improvements have enhanced the speed and accuracy of E-Verify. With 137,000 employers now enrolled, only 0.3 percent of 6.4 million queries they have made so far in the 2009 fiscal year have resulted in denials that later proved incorrect, the officials say. That, opponents note, still means false denials for more than 19,000 people.

In addition, Ms. Napolitano has expanded a program that runs immigration checks on every person booked into local jails in some cities. And she recently announced the expansion of another program, known as 287(g) for the provision of the statute authorizing it, that allows for cooperation between federal immigration agents and state and local police agencies.

In extending 287(g), federal officials also drew up a new agreement, which all of some 66 localities currently participating have been asked to sign, that is intended to enhance federal oversight and clarify the priority on deporting those immigrants who are criminal fugitives or are already behind bars.