The rate of arrests in areas of Virginia with large immigrant populations is far lower than in communities with predominantly U.S.-born residents, a report released Friday by George Mason University shows.

The findings are meant to put into perspective the worries over increased violence from the international gang Mara Salvatrucha, or MS-13, said James Witte, director of George Mason's Institute for Immigration Research. Such concerns have become a divisive issue in Tuesday's gubernatorial election in Virginia.

Witte said several of his students recently approached him, bothered by television ads aired by Republican candidate Ed Gillespie that called MS-13 an increasing menace in the state and portrayed opponent Lt. Gov. Ralph Northam (D) as soft in dealing with the problem.

Gillespie has also accused Northam of supporting "sanctuary cities" that decline to cooperate with federal agencies in enforcing immigration laws, despite the fact that there are no such localities in the commonwealth and that Northam says he has "always been opposed to sanctuary cities."

"That sort of advertisement and a lot of the rhetoric today is changing the discourse in what, we think, is a negative way," Witte said.

"There is a lot of support for immigrants and the economic role that they play, that they're not this evil threat," Witte said. "But when you get other people with loud voices making statements that are just not based in fact, it has the possibility that it begins to change public opinion."

A Gillespie spokesman said the ads are part of the Republican's emphasis on improving public safety in Virginia by cracking down on gangs.

"Ed is the only candidate in the race with a detailed plan to combat MS-13 and other gangs in Virginia to makes us safer, especially those in immigrant communities that are the most vulnerable to MS-13 violence," David Abrams, the spokesman, said in an email.

During the past year, several slayings tied to MS-13 have taken place in Northern Virginia, including the stabbing death of Damaris A. Reyes Rivas, 15, in a Springfield park in January. That case, now in a Fairfax County court, led to the arrest of 10 people connected to the gang, several of whom live in Fairfax, authorities said.

However, while some 300,000 immigrants live in Fairfax County, the rate of arrests for the county's entire population of 1.1 million residents is low, according to the George Mason report, which uses 2015 data from the Virginia State Police, the FBI and the Census Bureau.

That year, there were about 23,100 arrests in the county, equal to 2.1 percent of the overall population, the report shows. The report does not distinguish between gang-related arrests and other crimes, or between crimes committed by immigrants or native-born U.S. citizens.

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According to the study, the overall arrest rate in Virginia was 3.2 percent in 2015.

In Arlington County, home to roughly 53,000 immigrants, the arrest rate was 1.9 percent, while in Manassas City, with 11,400 immigrants — 27.3 percent of the total population — the rate was 3.6 percent.

Colonial Heights, near Richmond, has 1,160 immigrants in a population of 17,820 and an arrest rate of 17.5 percent, the study said. Danville, with 1,300 immigrants, has an arrest rate of 10.8 percent.

Jay Lanham, director of the Northern Virginia Regional Gang Task Force, said that regardless of the George Mason findings, the number of crimes in Northern Virginia perpetrated by immigrant gang members has risen recently.

"As far as the immigrant community as a whole goes, I wouldn't really know," Lanham said. But "our arrest numbers are up significantly compared to last year."