While you cannot foresee all the effects of your actions this does not exonerate you from accepting responsibility for the consequences. Given that the nurse would still be alive if this prank had not been perpetrated the radio station, 2dayfm, is responsible for her death, albeit unintentionally. This IMO is made worse by the statement from the radio station that it had not broken any laws, in spite of the the fact that they did not get their permission to broadcast the nurses, even though this is a requirement in Australia.
It will be interesting to see whether 2dayfm actually do anything to show that they recognise they have any responsibility for the results of their pranks.