A senior counter-terrorism detective was today found guilty of trying to sell information to the News of the World.
Detective Chief Inspector April Casburn committed a "gross breach" of the public's trust by calling the now-closed tabloid and offering details of the phone-hacking investigation in return for payment.
The 53-year-old was found guilty of one count of misconduct in public office by jurors at Southwark Crown Court.
She telephoned the Sunday newspaper early on September 11 2010 and spoke to journalist Tim Wood, complaining about pressure from Lord Prescott over the probe and giving the names of two former NotW journalists under investigation - Andy Coulson and Sean Hoare.
Casburn, from Hatfield Peverel in Essex remained impassive as the verdict was given.
Prosecutors said she tried to undermine the hacking investigation by offering to leak details to a tabloid newspaper.
Mark Bryant-Heron told the jury: "She sought to undermine a highly sensitive and high profile investigation at the point of its launch.
"It was a gross breach of the trust that the public places in a police officer not to disclose information on a current investigation in an unauthorised way, or to offer to do so in the future for payment."
He said that her conduct was "disgraceful" and the phone call was "malicious".
Casburn admitted contacting the newspaper, but denied asking for money or offering any information that was not already in the public domain.
She was not working on the probe, called Operation Varec, but colleagues in the counter-terrorism command were running the investigation.
The detective, who joined the force in 1993, claimed she feared colleagues saw the phone hacking probe as "a bit of fun", getting to travel and meet celebrities, and worried about counter-terrorism resources being wasted.
But Mr Bryant-Heron said that she had not mentioned these concerns in the call, according to an email written by Mr Wood 15 minutes later.
Casburn will be sentenced later this month on a date to be fixed and was released on unconditional bail until then.
The court heard that she is currently in the process of adopting a three-year-old child.
Mr Justice Fulford said: "A real possibility is an immediate custodial sentence, but I'm obviously going to have to consider very carefully the issues that we've ventilated this afternoon and any other mitigation."
Speaking outside court, Detective Chief Superintendent Gordon Briggs, who is overseeing the inquiries into phone hacking, corrupt payments and other privacy breaches, said: "It's totally unacceptable for a serving police officer to leak confidential information to journalists for private gain. In doing so they let down the public and they let down their hard-working honest colleagues.
"To act in that way is a gross breach of public trust. I hope today's verdict demonstrates our commitment to rooting out this kind of corruption and demonstrates that corruption of this kind will not be tolerated in the Metropolitan Police Service."
Mr Briggs said this was not a case of whistle-blowing, despite Casburn's claims that she was concerned about counter-terrorism resources being wasted.
He said: "There may be occasions when putting certain information in the public domain, so-called whistle-blowing, may be tolerated; this is not one of them."
Greg McGill, a Crown Prosecution Service lawyer, said: "DCI Casburn has been found guilty of misconduct in public office - not only did she seek to divulge confidential information, she sought to leak details of a case to the very newspaper under investigation. This is a very serious offence and the jury has today agreed that DCI Casburn's actions were criminal."
IPCC deputy chairman Deborah Glass said: "DCI Casburn's conviction is a testament to the strenuous efforts being undertaken to identify police officers who may have taken corrupt payments. It also sends a strong message that the public can not and will not tolerate corruption from police officers.
"The IPCC will continue to intrusively supervise Operation Elveden to ensure that the Metropolitan Police Service is robust in rooting out corruption in its ranks."