The poisoning in the hospital

Six people were visiting Tycoon Tye in the hospital. Each of them entered the hospital once and only once, stayed there for some time, and then left. Furthermore, if two persons were in the hospital at the same time, then at least one of the two saw the other.

One person managed to poison the food that he was given. The detectives were called in and statements were taken:

• The wife said she saw the daughter and the son.
• The daughter said she saw the wife and the lawyer.
• The son said he saw the daughter and the manservant.
• The manservant said he saw the housekeeper and the lawyer.
• The housekeeper said she saw the wife and the lawyer.
• The lawyer said he saw the son and the manservant.

If only the culprit lied, who did it?