The Marblethwaites’ Safe

It was a cold and windy night when the Marblethwaites’ safe was broken into and three diamond rings, two watches, and an old diary full of secrets were stolen.

The Suspects were:

the butler

the nanny

the cook

the chauffeur

the family doctor

the veterinarian

Clues:

1. The thief was spotted by a neighbour and was seen to be wearing bluejeans and a green windbreaker.
2. Mr. Marblethwaite first met the thief when they were in Cub Scouts together in 1962. They were both 8 at the time.
3. The family doctor was the older brother of the veterinarian.
4. At the time of the theft, two men and a woman, all of whom were good friends but not relatives, were playing cards and eating tuna sandwiches in the kitchen.
5. The nanny was delighted when her only two brothers, the cook and the chauffeur, were hired to work at the Marblethwaites’. The nanny had no sisters.
6. The veterinarian was a vegan.
7. The butler received a call that night from his mother.
8. The nanny and the vet were almost exactly the same age.
9. Mr. and Mrs. Marblethwaite had hired the nanny to look after their fifth child when the nanny graduated from the London School of Fine Nannies. She was the youngest graduate of the school.
10. Mr. Marblethwaite had once been the cook’s camp counselor.

Who stole the items?