Here's a hint: being investigated by the police is not "personal reasons" or "some private matters". As Tracy Watkins points out, public office comes with strings as well as a Ministerial limousine, and one of those strings is fronting up and explaining why you've resigned. Especially when the Prime Minister says "If he hadn't resigned I would have sacked him".
On this, the government just looks shifty and secretive, as if they are trying to cover something up. Key has to come clean and explain why he would have sacked his Minister. Fortunately, we have a Question Time today, and he is likely to be pressed hard on it.
(Tui stolen from The Standard)
Update: Key on Worth:
"His conduct does not befit a minister. I will not have him in my Cabinet. I have lost confidence in him as a minister."So a) why didn't Key sack him a weel ago when he first learned of the problem (and not from Worth); and b) such strong condemnation now makes his earlier attempt at a coverup look all the more indefensible. Did he really think no-one would ask, or that we wouldn't find out that Worth was the subject of a criminal investigation? Is Key really that much of a fool?