Logic Puzzle!

You know that one logic puzzle with the labrynth guards? Well this is a copypasta of that with a twist, enjoy.

Three guards stand infront of three doors, one is the exit to the building, if you pick the wrong door you are stabbed, One always tells the truth, one always lies, and the 3rd stabs you if you ask questions more than 7 words long, and if you say more than 3 sentences.  What do?

All right, try this.

A trial was held to find a spy. The trial had three defendants: A, B and C. One of the defendants was a knight, who always tells the truth, one was a knave, who always lies, and the other was the spy, who can either tell the truth or lie.

During the trial, A either said "C is a knave" or "C is the spy," but we don't know which.
B either said "A is a knight," "A is a knave" or "A is the spy."
C either said "B is a knight," "B is a knave" or "B is the spy."

A logician who makes no mistakes was asked to solve this problem and claimed he did not have enough information. He was then told what exactly A had said and figured out who the spy is.

Who is the spy?