News of the World private investigator Glenn Mulcaire told journalists on the paper that he obtained the voicemail messages of missing schoolgirl Milly Dowler from a police source, a court heard.
Former News of the World chief reporter Neville Thurlbeck told the Edinburgh perjury trial of former News of the World editor Andy Coulson that he put the paper's private investigator Mulcaire on to the story when the Surrey schoolgirl went missing.
Thurlbeck, the tabloid's former chief reporter, also said that hacked messages were the source of a story about former Home Secretary David Blunkett having an affair.
Coulson, 47, the Prime Minister's former director of communications, is on trial at the High Court in Edinburgh accused of lying under oath in the 2010 perjury trial of former Socialist MSP Tommy Sheridan.
Prosecutors allege that Coulson falsely stated that, before the arrest of private investigator Glenn Mulcaire and News Of The World journalist Clive Goodman in 2006, he did not know that Goodman was involved in phone-hacking with Mulcaire. He denies the charges.
Jurors were shown a copy of a story about the missing schoolgirl that appeared in an edition of the paper on 14 April, 2002, with the headline "Milly Hoax Riddle Messages on Mobile Probed".
The story, which appeared at a point when Milly had been missing for more than three weeks, contained precise timings and words that appeared to have been left on her phone.
Thurlbeck told the court that he was looking after the newsdesk that week in the absence of Greg Miskiw, while Coulson, as deputy editor at the time, was filling in for editor Rebekah Brooks, then Wade.
He said the schoolgirl's disappearance was "right at the top of the news agenda" and Coulson had said he wanted to make sure that the paper "was all over this story".
Thurlbeck said he had instructed Mulcaire to get involved with the paper's investigation into the Milly Dowler case and to research all possible suspects, including members of the family.
He was shown a note taken from Mulcaire's house in 2006 which had the journalist's name at the top, as well as the date 10 April, 2002 and the names and telephone numbers of Milly's parents.
The witness said Coulson was "not initially" aware that the private investigator had been tasked with working on the story.
Advocate depute Richard Goddard, prosecuting, asked: "When did he become aware you had instructed Glenn Mulcaire?"
Thurlbeck responded: "When Glenn came back with voicemails".
He added: "He came back with a tip off. A voicemail which had been intercepted on her phone."
Goddard asked: "Did Mr Coulson tell you to take this recording straight to the police to help their inquiry?"
Thurlbeck said: "The short answer is no. Mulcaire said to me that the recording had been intercepted by his police contact.
"He said he was getting this information from an unofficial police contact which wouldn't be unusual from a good private detective.
"Therefore we believed for a very long time that the police were fully aware of this line of inquiry and therefore for us to go back to the police would be a pointless exercise as they already had it."
Asked what he had told Coulson when asked about where the information had come from he added: "That there was a police source who was revealing to us via Glenn the existence of these voicemails and the content of them."
Pressed by the advocate depute, he added: "I didn't have to explain who Glenn was".
He said Coulson had seen transcripts of the voicemails, one of which suggested that Milly might have been working via a recruitment agency at a factory in Telford.
The court heard the paper sent a team of about five reporters and photographers in the hope of discovering the schoolgirl at the business.
Asked why police had not been contacted, Thurlbeck said: "That was not my call. That would always be the editor's call.
"We were confident that the police had this because we were getting it from a police source." He said it seemed "beyond comprehension" that a team of murder detectives would have overlooked it.
Goddard said: "You say the decision not to even try taking this to police was a decision ultimately made by Andy Coulson?"
"Yes," the Thurlbeck replied.
He added: "He trusted the source because he trusted me."
The court later heard that the team of reporters and photographers dispatched to the factory in Telford did not manage to produce any material for the newspaper.
Asked about Coulson's reaction to this, Thurlbeck said: "He and I were both frustrated that we appeared to have fairly concrete evidence that Milly was there and yet we could find neither Milly nor any police presence. So there was obviously something wrong somewhere and we were frustrated because we couldn't understand why that was the case."
The newspaper then contacted the police to ask if they were investigating a link between Milly Dowler and the factory, the court heard.
The police were told that the newspaper's information had come from a school friend of Milly's in order to protect what was believed to be a very confidential police source, the jury heard.
Thurlbeck continued: "They (the police) were in denial that this was forming any part of their investigation. I believe there was some suggestion that there was a crank caller who had been affecting the investigation and had come on their radar."
Thurlbeck also told the court: "One must add, very importantly, that with regard to Milly, at no stage was Andy aware that the voicemails had been illegally intercepted."
Under cross examination, the witness agreed with defence QC Murdo Macleod, who said there had "never been any suggestion that the News of the World asked Glenn Mulcaire to hack her (Milly's) phone".
He also agreed that the hoax messages story had not been a big story for the paper. In one edition it had been placed on page 30, the court heard.
Asked whether Coulson had believed the alleged factory link to Milly to be "ridiculous", Thurlbeck replied: "I remember him being very frustrated about the disparity between the evidence that we had and the story that we didn't have."
Macleod later asked what the attitude to Coulson was among his colleagues.
"There was a superb, collegiate atmosphere on the paper," replied the witness.
Describing Coulson as a "dynamic young editor who had his heart and soul in the business", he went on: "I'd never seen the News of the World newspaper feeling more proud and more ebullient and pleased with its editor than we were under Andy's tenure."
Earlier the court heard that the story about David Blunkett's affair originated from the illegal interception of between 15 and 25 voicemails he left on the phone of the woman involved in 2004.
The court was shown an exclusive front page News of the World story written by Thurlbeck and printed on 15 August 2004 with the headline "Blunkett Affair with A Married Woman."
Thurlbeck, 53, told the court he first heard the messages around the late spring or early summer of 2004.
"I was contacted by Glenn Mulcaire who played me the tape of an interception down the phone," he told the court.
He said he then "rang Andy Coulson", who was on holiday at the time, and told him that he had been played a "voicemail message left by David Blunkett".
"I said it was our private investigator," he told the court.
He said Coulson initially reacted with "extreme caution" over the story and told him to stop.
When Coulson got back from holiday, a meeting was later held to discuss the public interest justification for the story, the court heard.
Asked what he told Coulson about the source of the story, he said: "I said it was done by Glenn, our private investigator."
Thurlbeck insisted he had not used the investigator's surname during the conversation.
Goddard put it to the witness: "You told Mr Coulson that the hacked voicemails in relation to Mr Blunkett had come from the News of the World's private investigator Glenn?"
"That's correct," Thurlbeck replied.