You are to investigate a murder mystery. You know that these statements are true.

1. Lord Hazelton, the murdered man was killed by a blow on the head with a brass candlestick

2. Either Lady Hazelton or the maid, Sara was in the dining room at the time of the murder

3. If the cook was in the kitchen at the time of the murder, then the butler killed Lord Hazelton with a fatal dose of strychnine

4. If the Lady Hazelton was in the dining room at the same time of the murder, the chauffeur killed Lord Hazelton

5. If the cook was not in the kitchen at the time of the murder then Sara was not in the dining room when the murder was committed

6. If Sara was in the dining room at the time of the murder, then the wine steward killed Lord Hazelton.

Who is the murderer?