Persons entering the US illegally are more inclined to criminal activity.
"the Government Accountability Office released two unsettling reports in 2005 on criminal aliens who are in prison for committing crimes in the United States, and issued an updated report in 2011.
The first report (GAO-05-337R) found that criminal aliens (both legal and illegal) make up 27 percent of all federal prisoners. Yet according to the Center for Immigration Studies, non-citizens are only about nine percent of the nation’s adult population. Thus, judging by the numbers in federal prisons alone, non-citizens commit federal crimes at three times the rate of citizens.
The findings in the second report (GAO-05-646R) are even more disturbing. This report looked at the criminal histories of 55,322 aliens that “entered the country illegally and were still illegally in the country at the time of their incarceration in federal or state prison or local jail during fiscal year 2003.” Those 55,322 illegal aliens had been arrested 459,614 times, an average of 8.3 arrests per illegal alien, and had committed almost 700,000 criminal offenses, an average of roughly 12.7 offenses per illegal alien.
Out of all of the arrests, 12 percent were for violent crimes such as murder, robbery, assault and sex-related crimes; 15 percent were for burglary, larceny, theft and property damage; 24 percent were for drug offenses; and the remaining offenses were for DUI, fraud, forgery, counterfeiting, weapons, immigration, and obstruction of justice.
The 2011 GAO report wasn’t much different. It looked at 251,000 criminal aliens in federal, state, and local prisons and jails. Those aliens were arrested nearly 1.7 million times for close to three million criminal offenses. Sixty-eight percent of those in federal prison and 66 percent of those in state prisons were from Mexico. Their offenses ranged from homicide and kidnapping to drugs, burglary, and larceny."