A Mexican national accused of living in the U.S. illegally was charged with murder Wednesday in the shooting death of a California police officer who pulled him over to check if he was driving drunk.

Gustavo Perez Arriaga made his first court appearance in the central California city of Modesto but did not enter a plea in last week's killing of Cpl. Ronil Singh of the tiny Newman Police Department.

Perez Arriaga's attorney, Stephen Foley, questioned his client's mental competency, leading the court to delay the case until the suspect gets a mental health evaluation, The Modesto Bee newspaper reported .

Perez Arriaga told the judge that his real name is Paulo Virgen Mendoza, but authorities were still referring to him as Perez Arriaga. A complaint lists three aliases for him, including Paulo Virgen Mendoza.

Singh's family and several of the Police Department's 12 officers attended the hearing. Dozens of people stood outside the courthouse holding signs that read, "Justice for Cpl. Ronil Singh" and "Back the Blue."

Perez Arriaga is set to return to court Feb. 7, when a court-appointed doctor will provide a report on his mental health, said John Goold, a spokesman for the Stanislaus County District Attorney's Office.

Perez Arriaga was arrested Friday after a dayslong manhunt as he prepared to flee to Mexico, officials said. He has two previous drunken driving arrests, authorities say.

The case has rekindled a debate over California's sanctuary law that limits cooperation with federal immigration authorities. President Donald Trump seized on the case to call for tougher border security amid a fight with congressional Democrats over funding for a border wall, which has forced a partial government shutdown.

Cpl. Singh was also an immigrant, coming to the U.S. legally from his native Fiji to pursue his dream of serving in law enforcement, authorities have said. He joined the Newman police force in 2011. The 33-year-old was married and had a 5-month-old son.

Two of Perez Arriaga's brothers, his girlfriend and four others were arrested on suspicion of helping him evade authorities.

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This story has been corrected to show that a typo for Cpl. was fixed in the fifth paragraph.