Immigrants, illegal and legal alike, aren't increasing crime in America, a new study says.

The study by the Immigration Policy Center found that male immigrants, ages 18-39, are five times less likely to be incarcerated than their American-born peers.

In the post 9/11 world, "terrorism and undocumented immigration are often mentioned in the same breath," said Ruben Rumbaut, an author of the report and professor of sociology at the University of California at Irvine.

Yet, he said, while immigration increased from 1994 to 2005, violent crime rates actually fell.

The numbers also show there's no scientific evidence that immigrants are more likely to commit crimes, Rumbaut said. That trend was true across the board for all races and ethnicities.

In all groups, those without a high school education were more likely to be incarcerated. But even among those immigrants least likely to have a high school diploma, incarceration rates were lower than for their native-born counterparts.

For example, for Mexican immigrants, among those unlikely to have a high school diploma, the incarceration rate was 0.7 percent in 2000 for men ages 18-39. That's compared to 5.9 percent of Americans of Mexican descent.

The study, "The Myth of Immigrant Criminality and the Paradox of Assimilation," was released to dispel myths that immigration leads to crime at a time when state and local governments are weighing in on the issue, said Ben Johnson, director of IPC, the research branch of the American Immigration Law Foundation, which supports comprehensive immigration reform.

In Utah, Rep. Glenn Donnelson, R-North Ogden, is sponsoring two bills he says address a growing segment of crime by undocumented immigrants — identity theft.

With just two working days remaining in the 2007 legislative session, Donnelson said he hopes HB156, which would require Utah employers to verify new hires' eligibility to work using a federal system, will receive a floor hearing.

He's also working on a Senate hearing for HB105, which passed the House. That bill would mean some state law enforcement officers would be deputized to enforce immigration laws during their routine duties.

"It's just another tool," Donnelson said. "I think it's necessary. If they are here driving without a license or with false documents ... through their normal course of duty, (officers) can proceed further."

While the study didn't find immigrants were prone to commit crimes, it did find that the children and grandchildren of immigrants were more likely to commit crimes than their parents.

"The pattern of adaptation goes in the opposite direction as if they are assimilating to not only the good but to the bad in American society," Rumbaut said.