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 Sept 11, 2010, and spoke to a 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 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 Bryant-Heron said 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 in the process of adopting a three-year-old child.
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.”
The prosecution said her actions were an attempt to undermine the investigation because of her perception that she had been wronged and sidelined by police colleagues.