WASHINGTON (AP) — The Biden administration struggled to properly vet and monitor the homes where they placed a surge of migrant children who arrived at the U.S.-Mexico border in 2021, according to a federal watchdog report released Thursday.

The Department of Health and Human Services is required to screen adults who volunteer to take in children arriving in the country without parents. But the analysis concluded that the department failed to prove it ran basic safety checks — like address or criminal background checks — on some adults who took in children. In about a third of the cases reviewed by the federal watchdog, the agency did not have legible documentation for the adults on file.

“We found that children’s case files and sponsor records were not always updated with important documentation and information,” said Haley Lubeck, an analyst for the HHS Office of Inspector General, which conducted the review.

The federal health agency responded to the report by saying it has improved the process and the report only shows a limited window into how the agency handled cases “during an unprecedented influx.” HHS said it has also added new training for its employees handling migrant children.

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“The overwhelmingly majority of findings and recommendations address records management and documentation issues that (the agency) has already improved through training, monitoring, technology, and evaluation,” said HHS spokesman Jeff Nesbit.

The report comes as President Joe Biden is facing intense pressure around his immigration policies. Since he took office, the administration has grappled with millions of migrants traveling to the border and faced scrutiny over how it handles children who arrive in the U.S. without parents. HHS, in particular, has been criticized for releasing those kids too quickly from government shelters, discharging them to adults who have allowed them to be exploited by major companies for cheap, dangerous, and illegal labor.

The federal watchdog analyzed the case files of more than 300 migrant children from early 2021, months after thousands of children had trekked to the U.S. border seeking asylum. In March and April of that year, HHS placed more than 16,000 children with adults.

HHS is supposed to obtain IDs for the adults – called sponsors – who take in migrant children.

But the federal watchdog found that illegible IDs were submitted to HHS in more than a third of the cases analyzed during that time. Some IDs had misspelled words or missing holograms, raising questions about whether they were forged documents.

The agency also failed to provide proof it had conducted basic safety checks – like background checks or address checks – in 15% of the cases, the watchdog found.

And, for every five cases, HHS didn’t follow up to check on the children it had placed, often for months.

HHS is supposed to have a follow up call with every child and their sponsor between 30 to 37 days after placement. But in cases where the agency failed to follow up with the children, it took on average about 122 days for a caseworker to reach out, the OIG’s analysis found.

The OIG’s investigations have previously found that the administration rushed to respond to the migrant surge in 2021, failing to adequately train staff dealing with the cases of children.