Brian Laundrie search: What is a 'person of interest'?

Florida police on Sept. 15 named fugitive Brian Laundrie a person of interest in their investigation into the disappearance of his now-deceased fiancée, 22-year-old Gabby Petito. Laundrie, 23, and Petito were traveling cross-country in a Ford transit van when Petito disappeared. Laundrie