In 1986, I had the good fortune to be asked to participate in a sheep capture and relocation by our California Fish and Game Dep't. We caught and relocated 32 California Bighorns, with most of them going to an area just on the east boundary of Yosemite National Park.
A few weeks after we let those sheep go, I was talking to the biologist who was keeping track of the sheep and he told me that we'd lost the one mature ram in the group. It had been walking along in deep snow and came to a crevice and apparently stepped off, not knowing it was there. He fell in an was wedged and eventually died there. It sounded very similar to what this looks like. Perhaps the same thing happened to this deer.