Since the Trump administration’s zero-tolerance policy that separated thousands of families at the border, the number of migrant children in government care has skyrocketed, reaching the highest numbers ever recorded. According to The New York Times, nearly 13,000 children are in the custody of Health and Human Services as of this month.

Relatives or family friends of a migrant child can apply to sponsor them, giving the child somewhere to live other than a government detention center while they await their day in immigration court. A new policy, however, requires all potential sponsors to undergo a fingerprint-based background check. This new process has allowed ICE to determine if the sponsors themselves are undocumented immigrants.

“We’ve arrested 41 individuals thus far,” ICE’s acting deputy director, Matthew Albence, said at a Senate committee hearing this Tuesday, The Guardian reports. “Our data that we’ve received thus far indicates close to 80% of the individuals that are either sponsors or household members of sponsors are here in the country illegally, and a large chunk of those are criminal aliens. So we will continue to pursue those individuals.”

According to an anonymous ICE officer who spoke to CNN, just 12 of those arrests were criminal; the remaining 29 were for immigration violations. Under the Obama administration, an individual’s immigrant status was not pertinent to their eligibility to care for a migrant child, and ICE did not prioritize these individuals. While this HHS policy is still in place, ICE is now using the sponsor applications to track down undocumented immigrants.

This practice vastly limits the number of available sponsors, however, leaving more children in government care. The financial burden of caring for so many has led the Trump administration to transfer more than $260 million away from programs like cancer research, HIV/AIDS prevention, and refugee support in order to care for the migrant children in detention, CNN reports.