malformalady:

Green discoloration of the lower abdomen, due to overgrowth of colonic bacteria during the putrefaction stage. Putrefaction is the process by which tissue is destroyed primarily through bacterial proliferation, which occurs soon after death. The first evidence of putrefaction is the development of a greenish discoloration to the skin usually in the lower right abdominal quadrant, although occasionally you may see it develop simultaneously or initially in the peri-umbilical or left lower abdominal regions. This is typically seen between 36 to 72 hours following death at a temperature of approximately 70 ˚F.