Olaf Reinstadler, a spokesperson for the Sulden Mountain Rescue Service, told German media that the avalanche on the 3,545-metre (11,630ft) mountain, also called Vertainspitze, could have been caused by recent snow drifts which had not bonded to the ice below.
He said climbing tours were popular and the weather conditions were good, but wondered why the mountaineers were climbing late in the afternoon, as the descent would have then taken until nightfall.
The bodies of the three people climbing together were recovered on Saturday before rescue efforts were suspended due to fading light and safety conditions.
The Alpine rescue service said that due to fog and low visibility, helicopters could not take off at first light on Sunday.
However, once conditions improved, rescuers and avalanche dog units were airlifted to 2,600 meters before setting out on foot.
By late morning, the bodies of the two missing mountaineers – the father and daughter – were found.