The police may have secretly obtained a court order to wiretap journalists from the Yediot Aharonot and Ma'ariv newspapers who handled and published leaked transcripts of Prime Minister Ehud Olmert's interrogation sessions last week, a former head investigator from the National Fraud Unit told The Jerusalem Post on Monday. Dep.-Cmdr. (ret.) Boaz Guttman, ex-chief investigator of the National Fraud Unit, said police had wiretapped a Haaretz journalist who published material pertaining to a criminal investigation into former prime minister Ariel Sharon five years ago, which was leaked to him by state prosecutor Leora Glatt-Berkowitz. Berkowitz was later convicted for a breach of duty. "Journalists have no immunity from this. Within the newspapers, someone had to verify that the leaked transcripts were authenticated, they had to receive guidance and background," Guttman added. "If police are wiretapping suspects in an [undercover] investigation into the leaks, they would have to wait patiently because such an operation would not bear fruits immediately," he said. Guttman said it was possible that law enforcement was giving the impression that no investigation had been launched while an undercover attempt to ascertain the source of the leak was already underway. Meanwhile, a Justice Ministry source said a formal investigation into the leaks could wait until the police complete their two most pressing criminal investigations into the premier. Olmert is under suspicion of illegally receiving hundreds of thousands of dollars from New York businessman Morris Talansky, as well as of double-billing charities and a government ministry for the same flights and using the excess to fund family travel arrangements. A number of former senior police officials have voiced the belief that the recent media leaks were an attempt by Olmert's sources to get law enforcement to launch a separate inquiry into how the information was transferred, thereby delaying an indictment of the prime minister. Olmert's spokesman has repeatedly denied that claim. "This isn't the first time there has been a leak," the Justice Ministry source said. "You don't have to play into the hands of the rivals of the investigation," he added. "The polygraph test won't change next month - why does it matter when the investigation is launched?" The source said a number of preliminary checks were currently being carried out to see whether an official investigation into the leaks would stand a chance of locating a culprit. "We need to see if we have a reasonable opportunity to find the source first," the source said. "It's not simple to launch such an investigation - there are over 90 people who were exposed to the investigation material, and it is not feasible to polygraph them all. So a preliminary fact-checking group has been established," he added. The source added that the chances of an investigation into the leaks being launched would be far higher "if we have some information," adding that it "is not a simple matter to go around interrogating journalists and see who met with them." The source said the preliminary checks would likely be completed between a week and 10 days from now. He listed a host of issues that the Justice Ministry was examining before deciding on whether to begin the investigation, such as locating a body to carry out the investigation. "Would it be the Police Investigations Department or the Shin Bet? Nothing as been decided. We are still thinking [about it]," the source said. Responding to the source's comments, Guttman said the Justice Ministry would be wise to hold off on an official investigation for the time being. "I always told my people, never let the other side dictate your behavior. The Justice Ministry's stance is reasonable. Law enforcement must not stray from the central aim, which is collecting evidence against Olmert." Meanwhile, Police Chief Insp.-Gen. Dudi Cohen again denied that police were responsible for the leaks. "The leaks from the investigations did not come from the police," he said during a visit to the Jewish Agency in Jerusalem on Monday. Cohen, who arrived at the Agency's headquarters along with senior police brass to learn about its world-wide activities, also denied a claim that National Fraud Unit investigators had failed to temporarily halt their search of the prime minister's bureau on Remembrance Day when sirens sounded to signal the traditional two minutes' silence. "This is an untrue charge. The officers present were the ones to turn to everyone with a request to stand during the silence. Any attempt to say otherwise is false," Cohen said. Responding to the comments, Olmert's spokesman Amir Dan said, "This is an absurd situation, in which the police commissioner is denying the police's leaks, while information from the police over the collected evidence continues to flow outwards without interference and in a tendentious manner. If the police don't have anything to hide, why have they refrained from launching an investigation into the leaks for an entire week?"