Dr. Carlos Franco-Paredes, an associate professor at the University of Colorado School of Medicine who has inspected immigration detention centers during the pandemic, said that several factors were to blame for the surge, including transfers of detainees between facilities, insufficient testing and lax Covid-19 safety measures. For example, he said, during a recent inspection at a center in Aurora, Colo., he saw many staff members who were not wearing face coverings properly, adding: “There is minimal to no accountability regarding their protocols.”