During the years of the Wall, around 5,000 people successfully defected to West Berlin. The number of people who died trying to cross the Wall, or as a result of the Wall's existence, has been disputed. The most vocal claims by Alexandra Hildebrandt, Director of the Checkpoint Charlie Museum and widow of the Museum's founder, estimated the death toll to be well above 200. A historic research group at the Centre for Contemporary History (ZZF) in Potsdam has confirmed at least 140 deaths. Prior official figures listed 98 as being killed.