Hannah Kobayashi’s family reported her missing. Police say she left voluntarily. What is her sister to do?

Hannah Kobayashi, a 30-year-old woman from Hawaii, stopped contacting her family last month after missing a flight and allegedly sending odd messages. Police determined she’d decided to vanish voluntarily – but the investigation, by authorities and amateurs, is dissecting her life... and much of it seems news to her family, writes Sheila Flynn