I have just been reminded how important it is to check references. A good friend has found herself in a situation where their new au pair, who had only been with them for six weeks, has robbed them. She is a 27 year old woman, so knew what she was doing. She even emptied the children's piggy banks! My friend now believes that this may not be the first time this particular person has done it.
Whilst this situation is obviously very rare, it just serves as a reminder to be cautious and to double check references as her were fake.