President Joe Biden is nominating a number of people to address the intensifying situation at the US-Mexico border, including Chris Magnus, the president’s pick to lead Customs and Border Protection. It’s a massive agency under Homeland Security; its employees take on a number of jobs ranging from checking passports at airports and other entry points to managing border crossings. The agency also encompasses the US Border Patrol. The World’s Monica Campbell tells us about Magnus, who is the current police chief of Tucson, Arizona, and what challenges he might face in a hugely politicized role.