There is a clue in the mirror about the situation at the time of the incident. You can obtain the clues by connecting the mirrors in the correct order using light. Then you can use a clock to go back in time.
Look around closely.
There are objects in the room that can reflect. You can use it to solve the puzzle.
Focus on the sound.
Listen to where the sound is coming from. You might get a hint about the puzzle.
Look at objects that seem to be reflective.
A special effect appears when a eyes reach an object. You can use this to see which objects are reflecting.