The BBC has been criticised by media lawyers for broadcasting an interview with a man arrested in connection with the Suffolk murders.
Details, including photographs, of Tom Stephens came from MySpace
They argued that the move could be prejudicial if Tom Stephens was charged and the case went to trial.
But the deputy director of BBC News, Adrian Van Klaveren, said he considered it to be "in the public interest".
Mr Stephens had been interviewed in the days before his arrest by journalists from the BBC and the Sunday Mirror.
The supermarket worker is being held on suspicion of murdering prostitutes Gemma Adams, Anneli Alderton, Tania Nicol, Paula Clennell and Annette Nicholls.
Police have said their inquiries are ongoing.
Christopher Sallon QC said he felt the decision to broadcast the story was "absolutely wrong" on the grounds that "it is contrary to the Contempt of Court Act" and "contrary to the spirit" of that legislation.
He told BBC Two's Newsnight programme: "It [the broadcast] can only encourage speculation and in my view, having seen the interview, prejudice the trial."
Media organisations have to ensure coverage of criminal cases does not influence a future jury's decision.
Once proceedings become "active", for example after someone has been arrested, care must be taken to avoid reporting anything which might create a "substantial risk of serious prejudice to a trial".
Defence lawyer Julian Young said such reporting "can be prejudicial" as the court may decide "there can't be a fair trial".
"The ultimate public interest must be a fair trial," he said.
However, Mr Van Klaveren said the BBC did consider whether it "could be prejudicing any potential legal action" and decided that this "was not the case".
He said: "We then had to think about the ethical issues around actually deciding to release a conversation which had been done on a different basis.
"We felt in these very extraordinary and very rare circumstances there was actually a justification for doing that."
Daily Telegraph legal editor Joshua Rozenberg said he thought that the amount of information put in the public domain should not have a great impact on any future trial.
He told BBC Radio 4's Today programme: "Juries are pretty robust, and they're always told to forget anything they may have read in the press, and the trial these days is usually up to a year after somebody is arrested.
"But if there has been a huge amount of publicity, cumulative publicity, and something unusual like an interview, or lots of photographs, then it might be quite difficult for the jury to ignore that and the impression it creates."
Former Gloucestershire chief constable Tony Butler said the media's appetite for information during a major criminal investigation could damage the prospect of a conviction.
His force investigated the Gloucester murders committed by Fred and Rosemary West, but was unable to call some witnesses who had sold their stories to the press.
"This case hopefully will be resolved in the courts, by a jury having sufficient evidence to conclude that the individual in the dock did in fact commit the murders... and you can't jeopardise that at any stage," he told Today.
Lawyer Mark Stephens told Newsnight that the changing nature of the media, and the way in which public access information, should be considered.
He said there had been "a sea change in the way in which we look at the media" which meant "we no longer take the BBC as writ".
"People actually interact with the media now. They go on the internet... people actually try to investigate.
"There has been a fundamental change. We as a society are much more enquiring, we are much more sceptical."