The suspect was identified as Gustavo Perez Arriaga and was arrested in Bakersfield, about 280 miles southeast of Newman, where Police Cpl.
The Stanislaus County Sheriff said Singh was conducting a traffic stop for a suspicion of driving under the influence when the shooting occurred.
"He doesn't belong here, he is a criminal", Christianson said during a press conference Thursday while they were still searching for Arriaga.
"While we absolutely need to stay focused on Officer Singh's service and sacrifice, we can't ignore the fact that this could've been preventable", Christianson said, noting how Arriaga had several run-ins with police - which couldn't be reported to ICE on account of California's sanctuary law.
It was not immediately clear if Arriaga had an attorney. "Law enforcement was prohibited because of sanctuary laws and that led to the encounter with Officer Singh".
Christianson condemned sanctuary laws, which he said prevented local law enforcement from sharing news of Arriaga's two previous DUI arrests with Immigration and Customs Enforcement.
"California law fully permits the sharing of information on risky gang members", spokesman Evan Westrup said.
Christianson said the two men "intentionally lied to us, tried to divert us, they misled us, they provided informartion that was false, all in an attempt to protect their brother".
California Governor Jerry Brown, a Democrat, in signing the bill into law said it provided reassurance to undocumented immigrants without sacrificing public safety.
Sac Bee: Suspect in Newman Officer Killing Arrested in Bakersfield
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This undated photo provided by the Newman Police Department shows officer Ronil Singh of Newman Police Department who was killed by an unidentified suspect.
On Thursday, meanwhile, authorities announced that the suspect is an illegal immigrant in the U.S. His brother Reggie, who spoke on their behalf, thanked law enforcement for catching the suspect.
Officers found Singh who had been shot, and he was taken to hospital where he was pronounced dead. He also said that Arriaga was a Sureno gang member and has several aliases and social media accounts. He said both men were also in the country illegally.
Adrian Virgen and Erik Razo Quiroz were arrested yesterday for allegedly helping Arriaga escape after he allegedly shot and killed Corporal Singh.
Singh was born in Fiji and had been working for the Newman Police Department since 2011. He called the 33-year-old with a newborn son an "American patriot".
Newman Police Chief Randy Richardson highlighted the department was just 12-members and that he relieved Singh on Christmas Day so he could spend some time with his family.
The Kern County Sheriff's Office told Fox News it will hold its own press conference an hour later.
English was Singh's third language and he had a thick accent but took speech classes to improve his communication, the chief said.
Three people were also arrested at the home, Youngblood said.
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The talks will allow the two sides to "bring complete clarity and synchronise actions" going forward, Mr Peskov said. Foreign ministers, intelligence, and defence ministers will discuss the situation from all angles there.