Grand jury is so named because traditionally it has greater number of jurors than trial jury, called a petit jury (from the French word petit meaning small).
Although mice tend to come out in the night when most of the occupants of the house are asleep or immobile. This allows them to stealthily infiltrate any of your food bags, crumbs etc. During the day time, mice will normally not come out, but if opportunities exist then they surely can.
#2 â there might be a dead mouse/animal somewhere. During the winter, mice and other critters want to come in from the cold and live in your home. In my area, the field mice flood in ever winter. This can be reduced by having a well sealed house, but theyâre clever and theyâll find any little opening to get in.