The misuse of Quote Marks

There is nothing so irritating as the press' misuse of quote marks to bring into question the validity of a statement. This headline from the BBC is partularly egregious. It reads "Elderly woman 'killed by burglar'. " Why quote marks? This is not a direct quotation and if it is why use it as a direct quote. It is a strait foreword statement that the paper can make on its own. Is it in doubt that she was killed? Do they think the police are not telling the truth about the killer being a burglar? If they just don't want to assert the fact on their own, the headline could have read "Elderly woman killed by burglar Police Say" or "police believe woman killed by burglar." Why the quote marks?