There is provided a grid system (10) containing a set of stakes (40), a grid (20) and a key (3) that can be transported to a crime scene to create a working area in which evidence can be accurately cataloged as to its precise location at the time of its discovery. The grid strings (21) are secured to the grid rings (22, 23, 24) to form a grid (20). The grid rings (22, 23, 24) attach to the stakes (40). The key (30), which also attaches to the stakes (40) ensures that the grid (2) is square. The preferred embodiment features a key (30) comprising two key rings (32) and a key string (31). The key (30), when fully extended to opposite corners of the grid (20), forms the shared hypotenuse to the right triangles on either side of the key (30) formed by the grid (20), thereby forming a grid system (10) The stakes (40) can be ribbed in a way to enable the grid rings (22, 23, 24, 32) to remain at a distinct position along the stake (40). This enables the grid rings (22, 23, 24) to be placed at a particular height along the stakes (40) to better control the distance the grid (20) is from the ground to help with leveling and measuring purposes.