The Crown Prosecution Service said there was no evidence to support a charge of manslaughter over the death of nurse Jacintha Saldanha, and that they would not be able to extradite the pair for data protection offences.[break]
It said that while misguided and with tragic consequences "the telephone call was intended as a harmless prank."
Radio hosts Mel Greig and Michael Christian posed as Queen Elizabeth II, William´s father Prince Charles, and one of the queen´s corgi dogs when they called the private King Edward VII´s Hospital in London in early December.
Indian-born Saldanha inadvertently put them through to Kate´s room where another employee revealed details of Kate´s recovery from severe morning sickness, which were then broadcast by their Sydney-based radio station.
An inquest heard that Saldanha, a mother of two, was found hanged in staff accommodation at the hospital several days later and there were no suspicious circumstances over her death. She also had marks on her wrist.
Malcolm McHaffie, Deputy Head of Special Crime at the Crown Prosecution Service, said police had handed them a file on the case and asked advice about whether a prosecution should be brought.
"Having carefully reviewed the evidence currently available we have concluded that there is no evidence to support a charge of manslaughter," he said in a statement.
He added that while there was "some evidence to warrant further investigation" of data protection and malicious communications offences, "any potential prosecution would not be in the public interest."
"In reaching this decision, the CPS has taken into account the following, among other, matters," he said.
"It is not possible to extradite individuals from Australia in respect of the potential offences in question.
"However misguided, the telephone call was intended as a harmless prank."
McHaffie added: "The consequences in this case were very sad. We send our sincere condolences to Jacintha Saldanha´s family."
There was no immediate reaction from Greig or Christian, or from Saldanha´s family.
The Austereo radio network revealed on Monday that Greig and Christian have been taken off air permanently following the call, which also resulted in them receiving death threats over the hoax.
Austereo suspended prank calls by its stations and pledged at least Aus$500,000 (US$520,000) to help Saldanha´s grieving family. Greig and Christian also made a tearful televised apology.
Australia´s media watchdog has opened an investigation into the call.
Saldanha was buried in her native southwestern Indian state of Karnataka in December.
She left three notes, one of which reportedly criticised colleagues over her treatment at the hospital.
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