The 15-month jail sentence on Detective chief inspector April Casburn for "trying to sell" information about the Met's phone-hacking inquiry to the News of the World is one of the most chilling developments yet in the phone-hacking scandal.
It blows apart the whole framework of journalists protecting the confidentiality of their informants.
And the man who makes that clear is News of the World reporter Tim Wood whose evidence in court contributed to the jailing of Casburn.
Wood, now a contributing editor of Exaro the news website, has launched a scathing attack on News Corporation for its role in the case.
He is furious that News Corp handed over an email he had written, which Justice Fulford said was crucial to 53-year-old Detective Chief Inspector Apri Casburn's conviction .
Wood took the call when Casburn phoned the News of the World early one Saturday morning in September 2010 to tip off the paper that Scotland Yard was launching a new phone-hacking investigation.
Wood writes on Exaro that the decision by News Corp's management and standards committee to hand over his email was a "betrayal" of one of the most basic principles of journalism, which is "always to protect the source" of a story.
"The MSC was established to counter damaging claims of a cover-up at News International over phone hacking," Wood told Exaro News.
"But I believe that it has gone too far, betraying more confidential sources than any other body or person in the history of journalism."
Wood said in his 30-year reporting career he has been quizzed four times about his sources by police but has not once breached the "tenet of journalism", which is never to reveal sources.
He added that the MSC's decision to hand over evidence that can potentially lead to sources being identified threatens the work of all journalists.
Patrick Gibbs QC, representing Casburn, had asked the judge to suspend the sentence, arguing that what she had done did not amount to a "breach in relation to counter-terrorism" or "a breach in relation to hacking", he said
Gibbs said Casburn, who worked for the anti-terrorist unit, had phoned the paper at 7.51am on a Saturday on her way to Tesco. "She rang and made an almost inexplicable call," he added.
The call was made out of frustration about resources being diverted from counter-terrorism to phone hacking and that in addition she had been bullied at work and was going through a divorce and an adoption process.
"It was about being very unhappy at work and making a mad telephone call," Gibbs said.
However, the judge said the evidence provided by Wood who took the call from Casburn and noted her request for money, was convincing and he did not accept that this was "an understandable case of whistleblowing". Yet Casburn did not give her name and Wood himself says his memory of the incident was "vague". He said Casburn was not trying to sell her story.
In a statement, the Met described Caburn's call as a corrupt attempt to make money out of a sensitive and potentially very damaging information . But Casburn denied asking for money and no story ever appeared.
What DID Casburn want ? Wood told Exaro she was not seeking money for a story but "seeking reward in return for information that might help a large corporation defend itself against damaging allegations".
The judge said he found Wood to be a "reliable and honest and disinterested witness", who had taken the trouble to make a careful note of the conversation to pass on to his boss.
Casburn is the first person to be convicted and sentenced in a case connected to the News of the World phone-hacking investigation, which was reopened in January 2011 and has led to the arrest of more than 95 people.
Casburn sat composed throughout the hour-long hearing on Friday morning, said the Guardian. On being sentenced, she turned to the public gallery overhead and blew a kiss.
Meantime that central pillar of investigative journalism - the whistleblower's trust in the reporter - has been consigned to the funeral pyre of history.