Urban Legend: A suicide by hanging was mistaken for a Halloween decoration.

True.
On 26 October 2005, the corpse of a 42-year-old woman was left suspended in public view for hours in Frederica, Delaware, because her lifeless body was assumed to be yet another Halloween display. The unnamed woman hung herself from a tree located across a moderately busy road from some homes. Her body, suspended about 15 feet above the ground, could easily be seen from passing vehicles.
State police spokesman Cpl. Jeff Oldham and neighbors said people noticed the body around 7:30 that morning but dismissed it as a holiday prank. Authorities arrived at the scene at 11:00 to begin the process of examining the scene and removing the body.
Urban Legends Reference Pages: Horrors (Bough’d Out)