A top federal prosecutor in California said federal investigators have determined that all 20,000 people they flagged on the state's voter rolls as "likely noncitizens" are not U.S. citizens.

Bill Essayli, the first assistant U.S. attorney for California's Central District, told Fox News Digital that federal investigators have evidence that these 20,000 individuals received mail ballots this month. His office sued California last week seeking a court order to prevent any ballots they return from being counted.

"We're not asking California to take any drastic steps other than to sequester the ballots from the suspected noncitizens," Essayli said in an interview on Wednesday. "We believe it's at a minimum of 20,000. That's the floor." The potential ceiling, he said, is much larger. Essayli referenced a letter Homeland Security Secretary Markwayne Mullin sent to California in July that flagged nearly 200,000 voters as possible noncitizens.

DOJ OFFICIAL DEFENDS TRUMP'S NONCITIZEN VOTER PROBE ON '60 MINUTES,' ACCUSES SHOW OF EDITING OUT HER ANSWERS Since then, federal investigators have been sifting through those records to identify people they believe they can verify as noncitizens.

He said 20,000 is only the current tally and expects thousands more names to be added in the coming days.

Earlier this week, Essayli got into a social media spat with Gov. Gavin Newsom over the state's safeguards against noncitizen voting.

Essayli argued that California is allowing people without citizenship onto the voter rolls through its supposedly lax verification processes, while Newsom said the state follows all relevant federal law governing the integrity of elections.

In court filings, California election officials have pushed back against the Justice Department's demands, arguing that county election offices lack both the authority and access to federal records needed to verify voters' citizenship status.

They have also said that sequestering ballots from people on the DOJ list is impossible in cases where the ballots have already been processed. Once a ballot's signature is verified, it is removed from its identifying envelope and processed alongside other ballots, meaning it can no longer be traced back to an individual voter.

"That is true. That's why we're getting an emergency court order requiring them to put those ballots aside," Essayli said. "Ballots have already gone out, people are filling them out and they're being returned in process as we speak. So, the crime is occurring in real time." The DOJ escalated its push for immediate court intervention Wednesday, asking the judge to rule on its emergency request by noon Thursday. In Los Angeles County alone, officials have already processed 331,000 ballots, according to court records.

Essayli's office filed suit on Oct. 15, roughly two weeks after California sent out mail ballots, including to the possible noncitizens on the DOJ list, according to the federal government.

When asked why the Justice Department didn't act sooner, Essayli explained that investigators did not know exactly which voters would receive ballots until they were sent.

He said California should cooperate with the federal government to expedite the process of verifying voters' citizenship.

That would involve providing additional identifying information, including driver's license numbers and Social Security numbers when available, that federal investigators could cross-check against government databases.

California and dozens of other states treat this information as confidential and have refused to turn it over to the federal government, prompting the DOJ to take several of them to court.

In a separate lawsuit from Sept. 2025, the DOJ tried to compel California to provide its complete, unredacted voter-registration database, including names, Social Security numbers, home addresses and voting histories.

In January, a district court sided with California and dismissed the case, calling the government's request "unprecedented and illegal." The DOJ appealed the ruling and litigation is ongoing.

"If California will make available or submit its records, we can quickly put them through our established systems to determine who's a citizen and who's not," Essayli told Fox News Digital. "They're forcing us to do it the hard way, which we're willing to do because this is very important." He said every person on the current 20,000-name list was individually reviewed by a federal employee at U.S. Citizenship and Immigration Services and Homeland Security Investigations.

California officials, however, have questioned the reliability of the DOJ list.

Monica Flores, an assistant registrar-recorder in Los Angeles County, said in a court declaration that her office conducted a preliminary review of a sample of 200 records from the list that were associated with LA County addresses.

Of those, 112 corresponded to canceled or inactive voter registrations, meaning no ballot was mailed to those individuals for the November election, Flores said.

"I don't believe that, actually," Essayli said. "The information we have is that they likely received ballots. So we are asking for the names of people they claim whose registration has been canceled." Essayli added LA County did not say when these registrations were canceled. He raised the possibility at least some were canceled after federal officials provided the state with their list.

"If they're canceling now based on the records we provided, that's great news," Essayli said. "But that's all to be determined."

In the 200-person sample reviewed by LA County, Flores said that among records where birthplace was "meaningfully reported," 38.9% indicated the person was born in the United States, which she called "strong evidence of citizenship." Essayli similarly disputed this conclusion, arguing that the birthplace information — much like the citizenship information itself — was provided by the registered voters themselves.

"They're not independently checking any of this information," Essayli said. "They're going off the information that was provided to them by the person who registered to vote." The California Secretary of State's office and the LA County Registrar-Recorder's office did not immediately respond to Fox News Digital's requests for comment.

Essayli said that his office is determined to follow through with its investigation because "one noncitizen voting is too many."

"One illegal vote cancels out the vote of an American citizen. There are a lot of local elections that are decided on very few votes," he said. "Noncitizens cannot vote in federal elections, and we intend to enforce that law."