The statement revealed in court papers raises questions about the reliability of the list of 20,000 people in California

The statement, made in court papers, raises further questions about the reliability of a list of 20,000 people the justice department provided to election officials in Los Angeles last week. The department sent the county and California secretary of state the list last week and gave them a 48-hour deadline to segregate ballots cast from anyone on the list unless they could verify their citizenship. California election officials refused and the Department of Justice sued them on Thursday.

The Department of Homeland Security (DHS), which has compiled the list of non-citizens on the rolls, has resisted state demands to share its methodology for matching voter rolls for non-citizen records. Experts have warned that the way DHS is trying to match voter rolls to its own records could be error-prone.

Indeed, the DHS does not have a good track record so far. In July, it accused Nevada of having as many as 16,000 non-citizens on its voter rolls. DHS officials later sent Nevada election officials a list of 185 people it believed were non-citizens. Nevada officials responded by investigating the list and said all 185 were in fact citizens.