The New York Times has a very disturbing article on Hiu Lui Ng, who died in custody.
Ng had a fractured spine and advanced cancer. Both had gone untreated for months. It appears USCIS' failure to treat him, and other detainees with severe medical conditions, was willful.
Ng, a Hong Konger, applied for asylum but was denied. USCIS, then INS, mistakenly mailed a notice for him to appear in immigration court to the wrong address. Ng married an American, who petitioned for his permanent residency; USCIS arrested him at an interview for that process.
The Times has several articles highlighting the atrocious treatment of detainees in USCIS custody, and of their complete lack of oversight.