NIOD investigation
In 2003, the Netherlands Institute for War Documentation investigates both theories related to the new suspects:
Lena Hartog-van Bladeren and Tonny Ahlers. Both hypotheses are carefully considered and found not to carry enough weight.
Too late to find out
The NIOD's report therefore concludes: "Unfortunately, we are bound to abide by what we concluded in 1986: 'It is impossible to reconstruct the actual events.' Of course this is regrettable, because we would naturally have liked to unmask the culprit(s) in order to complete this part of the Anne Frank story. That is not what has happened. The possibility cannot be ruled out that new betrayal hypotheses will be advanced in the future. We shall have to wait and see whether these hypotheses are based on [solid] source material."
You can download this report from the Netherlands Institute for War Documentation's website.