Level of Difficulty: Hard

You are called to investigate a murder in a house. There are six suspects of the murder. The corpse was found in the living room. You begin your investigation by asking all of them three questions.                                                                               

 Four people among the six suspects are liars. Thus, they speak at least one lie but not necessarily all lies. It is confirmed that one of them is a murderer.

The responses of all six people are as given below:

Suho-

Chen was in the 2nd bedroom.

So was I.

Kris was in the bathroom.

Eunji:

I agree with Suho that Kris was in the bathroom and Chen was in the 2nd bedroom.

But I think that Suho was in the living room, OH MY GOD!

Chen:

Eunji was in the kitchen with Sehun.

But I was in the bathroom.

Kris:

I still say Chen was in the 2nd bedroom and Minah was in the bathroom.

Suho was in the 1st bedroom.

Minah:

Chen was in the bathroom with Sehun.

And Eunji was in the kitchen.

Sehun:

Kris was in the kitchen.

And I was in the 2nd bedroom with Chen.

The house accommodates eight rooms: Living Room, 3 Bedrooms, Kitchen, Bathroom, Garage and Basement. Any number of people could have been present in any of the rooms at the same time.

Can you identity the killer, the four liars and the position of each one of them during the murder?

Solved by SHINeePretti, Well done!

Answer:  Let us suppose that Chen was not in the second bedroom. This proposes that Suho, Eunji, Kris and Sehun are liars. It infers that Chen and Minah speak truth. But that is not possible as they do not coincide on Sehun's location. Therefore, we are wrong with our assumption and Chen was in the second bedroom.
So far, we have established the fact that Chen was in the second bedroom. Additionally, Chen and Minah are liars.

Now, let us suppose that Suho speaks truth. This proposes that Kris was in the bathroom and Suho in the second bedroom. This infers that Eunji and Kris are liars as they told that Suho was not in the second bedroom. Also it implies that Sehun lied, as he said Kris was in kitchen. Therefore we have three new liars now, which totals the number of liars to 5, which contradicts the given situation in the question.
Hence, now we have established the fact that Suho is a liar.



Let us now suppose that Eunji speaks truth. This proposes that Suho was in the living room and Kris was in the Kitchen. This infers that Kris and Sehun are liars. But again, this is contradicting the situation as we have already established the fact that there are again 5 liars (counting above 3 established liars)
Therefore, now we have established that Eunji is a liar. Kris and Sehun speak truth. Minah was in the bathroom. Suho was in the first bedroom. Kris was in the kitchen. Sehun was in second bedroom with Chen.

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