(CNN) US Immigration and Customs Enforcement arrested 170 potential sponsors of unaccompanied minors who were in government custody from late July to late November, according to numbers released on Monday.

Of those arrested, 109 — about 64% — had no criminal record but were suspected of being in the US unlawfully, and 61 — about 36% — were classified as "criminal aliens," according to ICE.

The arrests stemmed from background checks done by ICE for the Department of Health and Human Services on potential sponsors for unaccompanied children. HHS is responsible for the care of migrant children who enter the US illegally until they can be released to family or a suitable sponsor is found.

During the approximately four-month period, background checks revealed that about 80% of all potential sponsors were undocumented.

The San Francisco Chronicle first reported the numbers.

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