 Darkening of the skin is also caused by decomposition . The staking of a swollen , decomposing body could cause the body to bleed and force the accumulated gases to escape the body . This could produce a groan @-@ like sound when the gases moved past the vocal cords , or a sound reminiscent of flatulence when they passed through the anus . The official reporting on the Petar Blagojevich case speaks of " other wild signs which I pass by out of high respect " . 
