Actually, they did say that they don't know certain things (as opposed to not being at liberty to speak about them). In reply to a question about whether they thought this was an abduction, Kevin Winker, the Director of Investigative Operations, said the following:
"We don't know where Mollie is, and I am not going to draw any conclusions about the circumstances of her disappearance, other than to say that it is not consistent with her pattern of behavior."
That means: they don't know where she is, and they don't know anything about how she got there.
"We don't know where Mollie is, and I am not going to draw any conclusions about the circumstances of her disappearance, other than to say that it is not consistent with her pattern of behavior."
That means: they don't know where she is, and they don't know anything about how she got there.