A co-worker of 32 YOM David Jones reports him overdue. He intended to summit Mount of the Holy Cross via Halo Ridge and then descend the standard route. He was supposed to call his co-worker at 1630 to let him know that he had made it safely down and was on his way home. The co-worker became worried for David after 1700 and at 1823 called SAR. David has lived in Colorado his whole life and had some hiking/mountaineering experience. His co-worker believed he would have not been prepared to stay the night.