Mr. Jones' body was found dead on Monday morning in his bed. An autopsy revealed that he was stabbed in the chest with a blade the day before. After a thorough search of the whole house, neither the murder weapon nor any evidence was found. Detective Shen questioned all the people in his house at the time of the crime for their alibi.

The Chef was in the Library looking for more recipes to add to his extensive menu.

The Maid was in the main corridor sweeping the floor.

The Secretary was in the dining hall enjoying a grilled cheese sandwich she whipped up.

The Butler was out in the front of the house checking the mailbox for mail.

The Guest who visited that day was in the lounge sipping some tea when he had to go and left a note on the table, leaving out the back where he had parked his car.

If all alibis are correct, nobody would be in the vicinity of anyone else. Everyone would be isolated.

Without further investigation, who is the main suspect?