UV Torch Clues
Scroll down for more clues and the answer.
Try shining the torch on something you found in one of the cases.
Shine the torch on the blank piece of paper you found in the first case you opened and use the number grid on evidence board to help you solve the puzzle.
The symbols revealed on the plain piece of paper found in the first case, match up with parts of the number grid on the evidence board. The answer is 7 5 2 9.