A

Sodium amytal capsules are coated with a strong blue dye; when many capsules are swallowed, the dye leaches out, staining the gastric contents and mucosa, so at autopsy the stomach appears bluish. Similar blue staining from capsule dyes has been documented in other sedative overdoses (e.g., flunitrazepam) (Balmaceda-Harmelink et al., 2004, PMID 15553282), supporting that the color comes from the capsule, not the drug’s chemistry. Oxalic acid produces a gray-white corroded mucosa, while arsenic causes a red velvety appearance, making them unlikely.