Everyone in our office was 100 percent sure that the cleaner was stealing food from the staff refrigerator. Things started disappearing every week.
Someone's lunch would be gone by afternoon, drinks would disappear, and leftovers wouldn't make it through the night. People started blaming the cleaner because she was usually the last person in the building.
One morning, someone left a camera facing the refrigerator. By lunchtime, everyone had already decided they finally had proof.