LOS ANGELES- Federal immigration agents have arrested 905 people in California in the past three weeks after a statewide search for those who had violated orders to leave the country. The operation was the latest in a series of national sweeps by Immigration and Customs Enforcement agents. The arrests were the result of collaboration among teams in Los Angeles, San Diego and San Francisco that began on May 5. “The focal point of this operation were people who had exhausted all of their due process in the courts,” said Lauren Mack, a spokeswoman for Immigration and Customs Enforcement in San Diego. “They have a final order of removal issued by a U.S. immigration judge, and they’ve failed to depart.”

In the process of seeking each person on the list, Ms. Mack said, agents often encountered friends, family members and others who had violated immigration laws.

“Agents may come to a house looking for a target, and someone answers the door, or there are other people in the house who have also violated immigration laws,” she said.

Brian DeMore, acting director of the federal Office of Detention and Removal Operations in Los Angeles, said agents took into custody any person they encountered during an arrest who had violated immigration laws. Agents set out with a target list of just over 1,500 “fugitive aliens,” Mr. DeMore said, referring to people who have ignored orders to leave the country.

In addition to the 495 of those found, 410 people were taken into custody on charges of violating immigration laws, he said. Other violations included returning after being deported, overstaying a visa, or living in the country without any legal documentation, Ms. Mack said. Over half of all arrested this month have been deported.  According to Immigration and Customs Enforcement, 25.7 percent of those caught in the sweeps had been convicted of crimes while in the country.