A murder has been committed in a house. You are a detective and have to find out the murderer.

You investigate by asking three questions to each of the six suspects. Out of those six suspects, four are liars. It is not necessary that they speak everything a lie. But in their answers, there must be at least one lie. One of the six is the murderer.

There are eight rooms in the house in which the murder has been committed: Kitchen, Living Room, Bathroom, Garage, Basement, 3 Bedrooms.

At the time of the murder, only the murderer was present in the killing room. Any number of people can be present in any of the other rooms at the same time.

Can you identify the murderer and the four liars? Also can you find out who was in which room?

The responses of all the suspects are mentioned below.

Joseph:
Peter was in the 2nd bedroom.
So was I.
David was in the bathroom.

Mandy:
I agree with Joseph that David was in the bathroom and Peter was in the 2nd bedroom.
But I think that Joseph was in the living room, OH MY GOD!

Peter:
Mandy was in the kitchen with Christopher.
But I was in the bathroom.

David:
I still say Peter was in the 2nd bedroom and Jennifer was in the bathroom.
Joseph was in the 1st bedroom.

Jennifer:
Peter was in the bathroom with Christopher.
And Mandy was in the kitchen.

Christopher:
David was in the kitchen.
And I was in the 2nd bedroom with Peter.

PS: The corpse was found in the Living Room.

Assume that Peter is not in the second bedroom. This suggests that Joseph, Mandy, David and Christopher are liars. This further suggests that Peter and Jennifer speak truth. But they cannot be as they do not correspond on Christopher's location. Hence we have assumed wrong and Peter is in second bedroom.
By saying that, we have established that Peter is in the second bedroom. Also, Peter and Jennifer are liars

Assume that Joseph speaks truth. This suggests that David is in the bathroom and Joseph in the second bedroom. This further suggests Mandy and David are liars as they told that Joseph was not in the second bedroom. Also suggests that Christopher lied, as he said David is in kitchen. Therefore, there are three new liars, totaling 5 liars, which is a contradiction given the situation in the question.
Thus, we have established that Joseph is a liar

Assume that Mandy speaks truth. This suggests that Joseph was in the living room and David in the Kitchen. This further suggests that David and Christopher are liars. But again, this contradicts as we have concluded that there are again 5 liars (including above 3 established liars)
Thus, we have established that Mandy is a liar. David and Christopher speak truth. Jennifer was in the bathroom. Joseph was in the first bedroom. David was in the kitchen. Christopher was in second bedroom with Peter.

The killer has to be Mandy as no one else was present in the living room

Discussion