Stanislaus County Sheriff Adam Christianson, who led the investigation, blamed California's sanctuary law for preventing local authorities from reporting Perez Arriaga to United States immigration officials for deportation after two previous drunken driving arrests.
Gustavo Perez Arriaga was arrested in Bakersfield in connection with Wednesday's shooting of Cpl. Seven other people, including Arriaga's girlfriend and brother, face charges of accessory after the fact, or aiding and abetting.
Arriaga's alleged accomplices were arrested separately in Hanford and Modesto, the sheriff said, and their alleged crimes consisted of lying to police.
Over his police radio, Singh called out "shots fired" and as police arrived at the scene of the traffic stop, they found the officer on the ground with a gunshot wound.
The Stanislaus County Sheriff's Department said it would address "significant developments" in the investigation during a news briefing early Friday afternoon.
Officer Singh was a native of Fiji and has been employed by Newman Police Department since July 2011.
"We have also arrested two of his brothers", Christianson said.
Christianson said Singh was conducting a traffic stop for a suspicion of driving under the influence when the shooting occurred. Ronil Singh in a downtown Newman plaza already glowing with Christmas lights.
Singh was the first officer to die in the line of duty, in a department with 12 sworn officers.
The suspect was an illegal immigrant from Mexico who has claimed to be involved with a criminal gang called the Sureños, Christianson said.
"He came to America with one objective, and that was to serve this country", Richardson said.
President Donald Trump, whose demand that Congress approve $5 billion for a US southern border wall has led to a partial government shutdown, tweeted Thursday about Singh's killing, ending with: "Time to get tough on Border Security".
Richardson said he appreciated the many tips to investigators into Singh's shooting, but he lamented that people want to remain anonymous in these situations.
In a press conference on Thursday, Christianson said, "We will relentlessly continue to hunt our suspect down and bring him to justice so that ... we can bring closure onto this community and this police department". Time to get tough on border security. Deputies said they were investigating who actually owned the truck.
His brother, Reggie Singh, spoke to the crowd while holding the slain officer's 5-month-old son, wrapped in a blanket against the winter chill.
Officials later revealed that the suspect was an illegal immigrant.
High-house-giant evacuated after cracking noises: residents may pick up things
They were not allowed back into their homes but were sent to an evacuation centre in central Sydney-the Royal Hall of Industries. A resident of the Opal Tower told the Nine News network he heard a "big bang" as if something in the building had "snapped".