Republican presidential frontrunner Donald Trump opened his California campaign in Costa Mesa last week, addressing thousands of supporters in a rambling speech that lasted more than an hour. Trump mostly stuck to this usual stump speech – attacking Ted Cruz, Hillary Clinton, and the media.

But in the latter part of his address, he made note of a sharp rise in local crime rates. We wanted to check out his claims.

Claim #1: Crime is up. 

"In Los Angeles, homicides are up 10.2 percent," Trump said. "Rapes are up 8.6 percent. Aggravated assaults are up 26.5 percent," he told the raucous crowd. “Your crime numbers, they’re going through the roof, and we can’t have it anymore.”

Trump's statistics are correct. He was citing LAPD statistics. Crime rates did rise significantly last year in Los Angeles and other major cities. However, what he leaves out is that crime levels are far below historic rates.

Last year, the city recorded 280 homicides. That was 26 more than 2014. But in 1990, there were 1,100 murders in Los Angeles.

"When you look at the long-term trends in Los Angeles, the arrows are pointing in the wrong direction for any sort of crime increase," said Franklin Zimring, director of the criminal justice research program at Boalt Hall’s Earl Warren Legal Institute at the University of California, Berkeley. "Homicides are not just lower, but vastly lower."

Claim #2: Illegal immigration is to blame for the crime spike

Trump was on much less solid ground when he blamed the crime spike on illegal immigration from Mexico.

To underscore his point, he opened his speech by ceding his podium to Jamiel Shaw Sr., whose son was shot and killed in Los Angeles by an immigrant in 2008. He also invited to the stage other locals whose loved ones were killed by immigrants.

As he has his entire campaign, Trump vowed to crack down on what he describes as a flood of illegal immigrants.

"We are going to build the wall," Trump added. "Mexico is going to pay for the wall."

What Trump never mentions is that government statistics show a sharp drop in illegal immigration. 

The United States Border Patrol reported 337,117 apprehensions nationwide last fiscal year, compared to 486,651 the year before, a 30 percent decline.  That's also a nearly 80 percent decline since the peak of apprehensions in fiscal year 2000, when more than 1.6 million apprehensions were made.

A 2015 Pew Research Center study also found that between 2009 and 2014, more Mexican nationals left the U.S. than came. The study found that an estimated 1 million Mexican nationals (including their U.S.-born children) left the U.S. to return to Mexico, but less than 900,000 migrated to the U.S. in the same time period.

Zimring also points out that decades of academic research has shown new immigrants tend to be law abiding.

"First generation immigrations of all kinds have extremely low crime rates," said Zimring. 

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