A review of more than 600 pages of messages by The Washington Post found that Gendron resolved in December to kill those he slurred as “replacers,” and decided in February to target Buffalo’s Tops grocery store based on its local African American population. In March, he performed a reconnaissance-style trip to monitor the store’s security and map out its aisles, the messages show. When a store guard confronted him about why he had repeatedly entered that day, Gendron made excuses and fled in what he described as “a close call,” the messages state.

Having identified the supermarket as “attack area 1,” Gendron detailed two additional Buffalo locations as areas at which to “shoot all blacks,” according to the messages, which showed that he had charted routes to each location, worked out the times needed for each shootout and assessed that more than three dozen people in all could be fatally shot.