Someone didn't take care of the animal properly. Once you kill a deer, you should field dress the beast asap to get the meat cooled down/drained of blood.
They probably gave the meat away becuase they knew it was nasty tasting. The process of spoiling starts as soon as your bullet/arrow hits.
Two brothers, lets call them Stanislaus and Kasimir, went deer hunting. Kasimir accidentally shot Stanislaus. He rushed to the hospital: "Doctor, doctor, is my brother gonna be okay?" The doctor replied: "Well, his wounds were not life threatening, he would have pulled through if you hadn't field dressed him."