The present disclosure refers to a method for manufacturing a secured window in an identification card. The method comprising embedding information in a transparent window of the identification card and covering the embedded information with a thermochromic layer on a first side of the transparent window. The thermochromic layer is configured to become substantially transparent when subjected to a level of heat greater than a determined threshold value. In addition the method comprises the step of covering a second side of the transparent window, opposite to the first side, with a further thermochromic layer, the further thermographic layer being configured to become substantially transparent when subjected to a level of heat greater than the determined threshold value, such that the embedded information becomes visible through the transparent window when both sides of the window are exposed to the level of heat greater than the determined threshold value.