Scotland Yard said the same team of detectives investigating the killing of BBC star Jill Dando is examining the death threat phoned in to the BBC's switchboard.
The newswoman was gunned down execution style Monday in front of her home. Police say her killing has all the signs of a professional hit.
BBC news head Tony Hall -- who was Dando's boss -- was put under police protection after the death threat was made. A spokesman for the broadcast company confirmed that additional security measures were being taken at all four of its buildings in London, including its broadcasting and production centers and its radio and BBC World Service departments.
Both the police and the BBC declined to give exact details on the security measures. "The BBC has strong security anyway, but we are not prepared to discuss matters of security," a Scotland Yard spokeswoman said.
The Mirror newspaper quoted the caller as identifying himself as a Serb supporter and saying: "We killed Jill Dando. We will kill Tony Hall next."
British Foreign Secretary Robin Cook told a news conference that Britain's security forces would follow up any threats made against journalists by people claiming to represent Serb groups.
"Our security services are very efficient and I'm quite sure that if they have any reason to believe that any specific journalists, like the head of the BBC, may be under a death threat, then they will make sure they have proper protection," Cook said.
Police said the theory that Dando was murdered by a Serb killer in revenge for the bombing last week of a Serbian television station in Belgrade in which at least 10 people were killed, was just one of several leads they were following.
Shortly before her murder the 37-year-old Dando had launched a televised appeal for aid for Kosovo refugees driven from their homes by Serbian forces.
With tragic irony, Dando for years had anchored a program, in which crimes were re-created to jog the public's memory, leading to many cases being solved.
Police are examining the hundreds of cases Miss Dando had dealt with as the host of Crimewatch UK to see if she may have been killed by someone with a grudge against the program, The Times of London reports.
Another theory is that Dando may have been the victim of a stalker. News reports said she'd had problems with at least one fan last year after becoming the subject of the 62-year-old man's fixation.
News of her death has dominated the British media, with every national newspaper devoting their front pages to the story and loving tributes to Dando, a familiar face on British television since 1988.
Prime Minister Tony Blair's spokesman said he was "deeplshocked," while Buckingham Palace said Queen Elizabeth II was "shocked and saddened" by the news.
BBC Director General Sir John Birt said the newswoman would forever be remembered for her "sweet, unaffected elegance."
Dando was engaged to be married on Sept. 25. She is survived by her father and a brother.
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