Can someone please help me with this geometry?

Question

anonymous · Answer

Nathan, Joshua, Michelle, and Denise were in a room where a porcelain vase was found broken. When an inquiry was conducted by the building caretaker, each made a statement.
 
Nathan: I did not break the vase.
Joshua: Denise did it.
Michelle: Denise lied when she said Michelle did it.
Denise: Michelle did it.
 
The caretaker knew that only one statement is not true and concluded that Nathan broke the vase.
 
Describe in complete sentences the method you use to show that the caretaker made an incorrect conclusion.

ganeshie8 · Answer

same question @ http://openstudy.com/users/ganeshie8#/updates/504b7f94e4b0985a7a58aa85

anonymous · Answer

If Nathan broke the vase => He is lying.
Also => Joshua is also lying. 
However, only one statement is not true.
Therefore Nathan did not break the vase.

hartnn · Answer

this question is asked so many times!! i myself have answered twice...

anonymous · Answer

There's no way to search the site for previous questions. haha sorry, @hartnn

hartnn · Answer

u can use ganeshie's link.

anonymous · Answer

But how do you say the caretaker made an error?