A team of researchers at Yale University have used publicly available satellite imagery and open-source information to document 21 sites in Russian-occupied Ukraine that are being used as a “filtration system” to detain Ukrainian prisoners using interrogation, detention and torture to determine levels of loyalty. Several million Ukrainians, including women, the elderly and children have passed through these camps. Marco Werman speaks with Nathaniel Raymond, executive director of the Humanitarian Research Lab at the Yale School of Public Health.