President Donald Trump’s administration is using federal prisons to detain some people arrested in its immigration crackdown, the federal Bureau of Prisons said Friday, returning to a strategy that drew allegations of mistreatment during his first term.

Specifics of detainments have been scarce, leaving it unclear whether the criminals being targeted make up a significant share of those being captured.

Massachusetts' new top federal prosecutor on Wednesday vowed to investigate local officials if they obstruct the ramped up immigration arrests being carried out by U.S. President Donald Trump's administration,