New evidence uncovered by the Metropolitan Police indicates that reporters at News International continued hacking phones for three years after two of their colleagues were caught and jailed for the offence.
The 2006 arrest of Glenn Mulcaire, the private investigator contracted to the tabloid, and Clive Goodman, its royal editor, and their subsequent jailing, was supposed to have been when the NOTW stopped its reporters from hacking the phones of celebrities, politicians and victims of crime. But the specialist Scotland Yard team investigating hacking, Operation Weeting, has found evidence which it believes shows hacking continued until 2009.
Details taken from notebooks seized from Mulcaire's home when he was arrested have generally been regarded as the core evidence which set the time-frame of the criminal activity. But the new evidence shows it went beyond that.
Counsel for the inquiry, Robert Jay QC, said: "According to the Met police, NI's hacking operation had certainly begun by 2002, Milly Dowler being the first known victim. The police believe it continued till at least 2009. The police belief is not derived from an analysis of the Mulcaire notebooks, which we know were seized in 2006."
The Independent had been told by a number of the hacked victims that they believed the police timetable was wrong and that the illegal activities of the NOTW must have gone on past Mulcaire and Goodman.
Mr Jay also said the illegal interception of messages may have begun as early as May 2001.
The Sun: Second Murdoch tabloid in frame for intercepting voice messages
The practice of listening in to private voicemail messages had spread beyond the News of the World to Britain's two other biggest red-top tabloids, The Sun and The Mirror, it was suggested at the Leveson Inquiry yesterday.
In an indication of the legal and reputational problems that the investigation into the practices of the press is set to cause for titles beyond Rupert Murdoch's News International, Robert Jay QC, the barrister acting for the inquiry, said it was possible that a name written on the notes of private investigator Glenn Mulcaire linked him to The Mirror.
It is the first time a non-Murdoch title has been linked to Mulcaire, who wrote the names of those who had commissioned him to intercept voicemails at the corner of his notes.
Explaining that evidence was emerging to suggest that hacking "was not limited" to NI, Mr Jay said: "It has been drawn to the Inquiry's attention there may be another corner name relating to The Mirror, but this is under investigation."
The hearing was told that the name of The Sun also appeared in the same way in Mulcaire's notes and had been cited by the actor Jude Law as part of a hacking damages claim against the NOTW's daily stablemate. NI has previously strongly denied Mr Law's allegations against The Sun and vowed to fight his claim.
Trinity Mirror, the publisher of The Mirror, said that its journalists operate within the law and the industry code, adding that the company had "no knowledge of ever using Glenn Mulcaire".
Glenn Mulcaire: 'At least 28' employees commissioned jailed investigator
News International's longstanding excuse that phone hacking was confined to one "rogue reporter" has been shattered by the revelation that evidence identifies "at least 27 other NI employees" commissioning the private investigator Glenn Mulcaire.
It has sometimes been assumed that hacking originated through a small number of key executives at the News of the World who were close to Mulcaire, and that detailed knowledge of what Mulcaire was up to was confined to a tight clique, including the paper's former royal editor, Clive Goodman – jailed with him in 2007.
But the new figure of 27 other Wapping employees destroys any notion that hacking was a secret limited to only a few journalists there.
Robert Jay, QC, counsel for the inquiry, said that based on material provided by police, it would not be unfair to describe the NI journalists' use of the illegal practice as "a thriving cottage industry".
In evidence which relates to Goodman and Mulcaire's trial in 2007, it was established that Mulcaire generally wrote the names of those who commissioned hacking from him in the top corner of his notebooks, which were seized by police in 2006 when they raided his home. Despite the discovery of 11,000 pages of evidence, though, only a limited prosecution was mounted.
Mr Jay described the illegal behaviour as "grubby" and as "underhand as it was high-handed", adding that "questions might be asked as to how high up in NI the metaphorical buck stops".
It was "clear that Goodman was not a rogue reporter", Mr Jay said, adding that aside from the new number of those involved, there was also "evidence of a significant quantity of illegal activity over a lengthy time period".
Mr Jay offered only codenames for those he described as "prolific users of Mulcaire's services". The codes, however, point to senior NOTW staff who have already been arrested.
Computer attack: Lawyers warn of 'Trojan Horse' virus
Computer engineers at the Royal Courts of Justice were last night examining the software and hard drives of computers belonging to two senior counsel after the sudden appearance of a "Trojan Horse" warning on their screens.
The warning of the virus – which can indicate that data from the infected machine can be seen by an outside party – came just after the lunch break. David Sherborne, counsel for victims who are core participants in the Leveson Inquiry, interrupted proceedings to claim the alert had suddenly appeared on one of his two desk screens.
The warning notice appeared in a red box marked with the words "Trojan Horse" notifying the threat, and the options to delete or ignore.
A counsel for The Guardian newspaper said she also had received the warning but had chosen to ignore it.
If the supposedly secure RCJ system has been hacked into, even for a hoax message, it will prove an embarrassment to an inquiry into the illegal access of personal data.
The potentially infected machine belonging to Mr Sherborne contains inquiry management files and documents connected to clients.
Lord Leveson said he wanted it "dealt with" and admitted he had been "thrown" by the sudden warning.
'Fake Sheikh': Mahmood set to reveal his methods
The News of the World's former star investigations reporter, the "Fake Sheikh" Mazher Mahmood, is to give evidence at the Leveson Inquiry. The entrapment specialist, who lured many of his victims dressed as a wealthy Arab businessman, has already given a full witness statement to the inquiry team.
Robert Jay, counsel to the inquiry, said "agent provocateur" techniques in which "the ends did not justify the means" would be explored when Mr Mahmood – who is now with The Sunday Times, gave evidence.
Source of the evidence: Mulcaire's notebook
When police arrived at Glenn Mulcaire's south London home in August 2006, much of the most devastating evidence that would help close the News of the World and taint the Murdoch dynasty was lying in a binbag in the private detective's garden shed.
Crucially, Mulcaire, who was contracted to the NOTW, was in the habit of writing the first name of the journalist to have commissioned him in the top corner of his documents. A fraction of this material, which runs to some 11,000 pages, was used to convict Mulcaire and NOTW royal editor Clive Goodman of eavesdropping on the messages of royal aides. But only now – six years after Scotland Yard first became aware of the phone-hacking scandal – is the full extent of Mulcaire's archive becoming clear.