Prime Minister Ehud Olmert will likely be indicted in two to three months, a former senior police officer told The Jerusalem Post on Tuesday. The source, who did not wish to be named, said the timing of the indictment depended on a number of factors, such as whether the prime minister "makes himself fully available" to police detectives, and whether he provided "full answers" to the questions put to him. The source added that the latest investigation, in which the premier is suspected of double-billing several charities and a government ministry and using the extra money to pay for family trips, has significantly added to the National Fraud Unit's workload and could delay an indictment by weeks while police complete lines of inquiry. He added that every allegedly unlawfully funded flight taken by Olmert or a member of his family required hours of work on the part of the police. The source said it was "unreasonable" for police to say which interrogation of Olmert would be the last, as new testimony or a new piece of evidence could always appear unexpectedly. Meanwhile, despite saying that last week's fourth interrogation "could be the last," police have scheduled a fifth session with the prime minister on Friday. Previous attempts by police to agree on a date and time with Olmert's lawyers have met with considerable difficulties and prompted accusations of evasion from Attorney-General Menahem Mazuz. However, this time, the National Fraud Unit had "no problems" scheduling the interrogation session, a police spokeswoman said. The session is expected to last two-and-a-half hours, and detectives will likely ask Olmert about the Olmertours and Talansky investigations. Last week, former senior National Fraud Unit investigator Dep.-Cmdr. (ret.) Boaz Guttman told the Post that an indictment could be ready by September 1. Guttman added that Olmert would receive one opportunity to challenge or delay the charges. After receiving notification of the impending indictment, Olmert would be legally permitted to call a hearing with state prosecutors behind closed doors to lay out his case for why the investigations against him were flawed. But prosecutors were unlikely to accept such an argument, since they have been working with the National Fraud Unit on the Olmert investigations from the moment they began, Guttman said.