Happened two times already. The player gets "You are dead"-screen suddenly, and a message into log:
%player_name% is losing connection
The character body then falls through any building, ignoring floors or obstacles and becomes irretrievable.

I've been playing with two allies both times and it is guaranteed I was not sniped. Both times I've been above ground level - observing territory from 3rd or 5th floor building.

Both cases featured moving near stairs.
The first case was on stairs of the Chernogorsk building near grain elevator, see picture for building type: http://i.imgur.com/rhkuiov.jpg
The second time it was the 3rd floor of Electrozavodsk hospital. See the similar report: http://feedback.dayzgame.com/view.php?id=4442