Their may be an un lethal area in a deer's chest but I have never seen it, and I would say that ant it. I have a rule that has always panned out for me, anywhere behind the shoulder and in front of the hind quarter, 4 inches down from the back and 4 inches up from the chest is a dead deer, may not find him but he/she is going to die. Any where else they may die or they may live on, until you get another shot or they die from old age, they are tough but a shot through the chest will take them down.I would say that is a wound from something else. JMO.
Pappy