Am currently reading this one about a true incident in 1959-
Nine experienced hikers in the Ural mountains went missing in midwinter, and when search parties found their tent on a mountain slope they weren't in it, and there were knife cuts where they'd slashed their way out in a hurry.
Their bodies were found scattered around the area up to a mile away, some had no shoes or clothes and had died of cold, and others had fractured skulls and broken bones.
The slope was only about 20 degrees so an avalanche probably never did it, and the mystery remains unsolved.