Christianson's criticism of sanctuary laws echoes sentiments often leveled by President Trump, who has repeatedly clashed with California over the enforcement of immigration rules.
It was not immediately clear if Arriaga had an attorney.
Gustavo Perez Arriaga, a 32-year-old Mexican national, was arrested Friday.
Ronil Singh came to the USA from his native Fiji to fulfill a lifelong dream of becoming an officer, joining a small-town police force in California and working to improve his English.
The suspect was an illegal immigrant from Mexico who has claimed to be involved with a criminal gang called the Sureños, Christianson said. He also noted that the suspect had been in the country for a number of years and was seeking to cross back into Mexico before the shooting occurred. Christianson didn't say when the 33-year-old came to the US but that the Mexico native has been living here for several years.
Perez Arriaga is accused of killing Cpl.
During a news conference on Friday, Christianson spoke out strongly against California's sanctuary laws.
"The law, in fact, does allow that and precisely enables local law enforcement officials to work with ICE when targeting criminals and gang members in particular", said Cohen, an ABC News contributor. The 33-year-old had gang affiliations and multiple Facebook pages with different names, Christianson said. "That's what we need to get back to, is community, that small town feeling, and let it grow".
California Governor Jerry Brown, a Democrat, in signing the bill into law said it provided reassurance to undocumented immigrants without sacrificing public safety.
Arriaga had prior arrests for driving under the influence and could have been subject to deportation, Christianson said. Jerry Brown says the law permits sharing information on unsafe gang members with federal authorities.
According to the Modesto Bee, Christianson met with President Trump in May at the White House to discuss immigration and sanctuary laws.
Bongino said on "Fox & Friends" that Singh - who legally immigrated to the USA from Fiji - was "everything that's right about this country".
However, multiple studies have found immigrants commit crimes at lower rates than USA -born citizens. Incensed by the tragedy, members of Congress introduced Kate's Law, which would mandate up to 10 to 25 years in prison for illegal immigrants in the US with a criminal history who had been previously deported.