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.
To release mice, you may either put on a pair of thick gloves and pick the mice up out of the cage to let them go or you may carefully tip the container over until it is lying on its side on the ground and let the mice run out. Check your trap often to ensure that any mice you catch do not starve or dehydrate. 2  If you need to keep mice for more than 24 hours before releasing them, provide them with a dish of water and a small amount of commercial mouse food or fresh or dried fruit.