LOS ANGELES (Reuters) - Scores of illegal immigrants, including a man wanted for murder and a convicted child molester, were arrested in Southern California raids this week, U.S. authorities said on Friday.

The sweeps in Orange County, south of Los Angeles, were part of an operation by U.S. Immigration and Customs Enforcement targeting “criminal aliens” -- defined as people in the country illegally who have also committed other crimes.

Of the 175 people arrested, 27 are criminal aliens and another 26 are “immigration fugitives” who had ignored deportation orders by a judge.

The raids were part of larger crackdown on immigration fugitives, which this year has resulted in the first ever decline in their number, to 632,189, according to an agency spokeswoman.

“ICE has been working to aggressively improve the systems that help us identify, target and remove fugitive aliens from the United States,” Julie Myers, assistant secretary of homeland security for ICE, said in a statement.

The U.S. Senate is still struggling with a massive immigration overhaul, backed by President George W. Bush, that would legalize millions of illegals despite furious opposition from conservatives.

California, which shares a border with Mexico, has been at the forefront of the debate as its immigrant population has swelled in the past four decades, driving the state’s population to more than 37 million.

Among those arrested in the raids was Almarez Reveles Gonzalo, 35, wanted in Mexico for the murder of his 74-year-old uncle, ICE said. He was turned over to Mexican authorities.

Also arrested was Jamie Pena-Martinez, 30, a Mexican national previously convicted of child molestation who was ordered deported.

Most of those arrested in the raids were Mexicans, but others came from India, Kenya, the Philippines and Columbia. Of the 175 arrested, ICE said, 100 had already been deported.