(IsraelNN.com) Prime Minister Ehud Olmert announced Wednesday night that he will step down from office when a new Kadima party leader is chosen in the September 17 primary, because “he recognized that the investigation evidence held by police is serious and solid,” according to a Wednesday night statement from Israeli police sources.

In what will be the fourth round of questioning in several months, police interrogators will go to the Prime Minister’s residence in Jerusalem to interview Olmert on the latest corruption scandal, police sources told Haaretz. In the so-called “Olmert Tours” affair, Olmert is accused of receiving duplicate funding for trips abroad for himself and his family, and investigators seem more confident than ever that they will have enough information to serve an indictment.

“The investigation Friday is expected to be difficult and uncomfortable for Olmert," said the police sources. "He will be confronted with evidence and documents that have accumulated against him, and it is a fair assumption that he already understands that this involves substantive evidence," they noted.

The latest affair involves duplicate payments made from government coffers to Rishon Tours, a travel agency that Olmert and his family used to arrange trips abroad.

'Anyone else would have already been arrested'
As happened in the investigations over Olmert’s Talansky affair, the Prime Minister’s Office allotted only two hours for police to question him on this case, despite their demand for more time. "Anyone else would have been arrested had similar suspicions been raised against him. Unlike any other suspect, Olmert is getting privileged treatment. He is setting the date and duration of the questioning," a police source said earlier this month regarding the previous round of questioning.

The Justice Ministry issued a statement earlier this month alleging that the prime minister requested financing for State trips abroad from several organizations simultaneously, also requesting funding from the State. Olmert then allegedly had Rishon Tours produce a separate receipt for each entity that he asked to finance the trips, as if that body were the sole sponsor.

Rishon Tours then deposited the money Olmert gained in this way into a private account the tour company established in his name, investigators allege. The police allege that the prime minister used the extra money to book and finance, through the agency, dozens of private trips for himself and his family.

In Friday’s investigation, Olmert will be asked to explain a collection of documents which police believe show him implementing this system with Rishon Tours acting as his accomplice. 

The investigation will focus on the years that Olmert served as the mayor of Jerusalem, from 1993-2003, as well as his term as Minister of Industry and Trade, which he held from 2003 to 2006. Police sources said recently that there is "a high probability" that Olmert will be indicted in the Olmer Tours affair.

'Not off the hook, but relatively safe for now'
After the prime minister’s announcement Wednesday night that he will not be seeking re-election, in effect declaring his resignation, police investigators said that as far as they are concerned, Olmert is still not off the hook. According to a spokeswoman for the National Fraud Unit, the surprise statement will have no bearing on the police probes.

"The investigation continues as normal. Detectives will question Olmert on Friday at his residence irrespective [of his announcement]," said the spokeswoman.

However, Olmert’s continued tenure for the next two months will hamper the police in reaching indictments against him.  "Olmert did not resign," said a law enforcement source said after the announcement. "From our point of view, he is still a serving prime minister and he has immunity. This has many implications on the investigation."