Sydney police are investigating death threats against the two DJs at the centre of the prank call to the King Edward VII hospital in London, where the Duchess of Cambridge was receiving treatment for severe morning sickness.
A police spokesperson said they had seized a letter, which contained "a number of threats". Police would not confirm the nature of the latest threat but it is thought it was directed against Michael Christian, who along with Mel Greig made the call that was followed by the suicide of Jacintha Saldanha, the nurse who answered the phone.
"Detectives are continuing their investigation into the matter and are attempting to identify the source of the letter," the spokesperson said.
Sydney media reported that a number of staff and senior management at the radio station had been moved into secure accommodation and given 24-hour security protection.
A spokesperson for the station's owners said: "The safety of our employees is an absolute priority. We have sensible measures in place, as we always do, to ensure our people are safe. This is now a matter for the police and we trust they will investigate any specific threats that emerge."
The death threats were reported in Australia following the opening of the inquest in London into the death of nurse Saldanha, 46, who was found dead in her apartment in the nurses' quarters of the hospital in Marylebone, central London. The inquest heard she had left three notes.
One note dealt with the hoax call by the DJs from 2Day FM, another detailed her requests for her funeral, and the third addressed her employers, the hospital and contained criticisms of staff there, the Guardian understands from two separate sources.
Since Saldanha's death, 2Day FM's Facebook page has been bombarded with angry messages criticising the DJs and the station for making the prank call.
Greig and Christian deleted their Twitter account last Saturday, shortly after news broke of Saldanha's death.
On Monday, the two DJs gave emotional interviews to commercial television, during which they described their devastation at the news of Saldanha's apparent suicide. Christian said they were "gutted, shattered, heartbroken".
They said no one could have foreseen the tragedy that followed their prank. The two declined to name who had come up with the idea of making the call and said they did not know what vetting process the interview went through before it was aired.
"It went through the processes of every other recorded bit that we do: from interviews to, you know, anything at all that gets recorded and passed on to the appropriate people, goes through the process, and we're told whether it's yes or no to play," Greig told Channel Seven.
The radio station's management said the prank call had been cleared by 2Day FM's lawyers before being broadcast. Rhys Holleran, chief executive of Southern Cross Austereo, which owns 2Day FM, said the station had tried to contact the hospital five times, without success, before putting the call to air. The hospital denies it was contacted.
On Thursday, Acma, the Australian government body that regulates commercial radio, launched an investigation into whether the station had broken the commercial radio code of practice. Acma has the power to revoke a station's licence.
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image: © Tim Parkinson