A homemade-looking box asking for "Letters of Support" has appeared outside the "Balloon Boy" family home in Colorado.

The box sits outside the home of Richard and Mayumi Heene, who are under fire after authorities began investigating them on suspicion of concocting a hoax that involved telling the world their six-year-old may be flying thousands of feet in the air in a homemade balloon.

The box, which has an opening on top, includes a hand-lettered note that reads "Letters of Support."