Questions such as this remind me of the Sef Gonzales case a number of years ago.
The law is quite unsettled in regard to these matters, although you should be aware of Charles Lloyd Property Group Pty Ltd v Buchanan [2013] - Which is a Victorian decision. The facts are somewhat similar in that this case involved a suicide.
In short - You have a duty to disclose it as it may well be held to be a material fact. Erring on the side of caution is best with these things. ie, disclose it.