A female climber was killed Saturday night or early Sunday morning while descending the Mountaineer's Route with a group of several others on Mount Whitney. At this time there seems to be an almost total lack of confirmed information about the incident. Sketchy reports from persons in the area were briefly available on the Whitney Portal Store message board. Unfortunately, due to the forum owner's policy regarding fatal accidents, that thread has been deleted.
From what I've heard, the party may have planned to watch the sunset atop Whitney and then descend back to Iceberg Lake. Or perhaps they planned to spend the night atop the summit, but changed their minds due to unfavorable conditions—it was an extremely cold night in the Sierra. I happened to be several miles north, climbing through the night toward Shepherd Pass at the time. It was very cold and windy.
Regardless, the snow at that elevation would have quickly frozen into ice after sundown, turning a challenging snowbound route into a technical ice climb. I myself would go to great lengths to avoid downclimbing in conditions like that without a rope and excellent anchors.
I can't help but wonder whether the group's experience level was of such a high caliber that they felt confident they could safely descend the icy chute in the dark. Or did they feel they had no other options? It is possible, given the large numbers of inexperienced climbers who attempt Whitney each year, that they were simply unaware of the extreme hazard they were exposing themselves to.
Deaths on Mount Whitney are unfortunately not entirely rare, particularly in the Winter and early Spring climbing seasons, particularly while climbers are descending either the Mountaineer's Route's upper chutes or the steep snowfield above Trail Camp. Whitney in Winter is a technical endeavor, requiring specialized skills and gear for safe travel, and subject to unpredictable weather and conditions.
If more substantiated information becomes available, I'll post links here.