Polak was former Mayor Uri Lupolianski's right hand man and served as chairman of the local Planning and Construction Committee which approved the extension of the controversial Holyland real estate project. He is suspected of accepting a bribe, brokering bribery, money laundering, breach of trust and conspiracy to commit a crime.
Polak, who served as deputy mayor from 2003, approved significant changes in the project as the committee chairman, including changing the area designated for hotels to a residential area – a move which yielded large profits for the project's contractors.
Lupolianski and his predecessor, Ehud Olmert, have been casting the responsibility for the changes made in the project on each other, but a Ynet inquiry revealed that the building rights were increased in both their terms.
Polak, who was asked about his involvement in the project, told Ynet two weeks ago that the regional committee was responsible for the changes. "I was not involved in this decision (about the project's nature). It was made in 1999," he claimed.
"The contractors present the plan and bring it to the examination of the professional ranks. A lot of time passes before it reaches the municipality," he added. "Only after the city engineer's recommendation, it reaches the local committee. If needed, there is a vote, but the local committee only makes the recommendation. The regional committee makes the final decision."
He joined the project's critics, saying that "the problem is that it looks like a long monster from every point you look at it in Jerusalem. From a design perspective, I would have preferred it to be slightly different, maybe not so long. It might look different on paper."
Polak currently serves as treasurer of the Beitar Illit Municipality. He served as a Knesset member for United Torah Judaism for about two weeks in the 17th Knesset after the death of Rabbi Avraham Ravitz.
Polak is known to be a "genius in numbers" and is said to have a phenomenal memory. He was considered in the past as a candidate to replace Lupolianski as Jerusalem mayor, but eventually lost to MK Meir Porush, who was defeated in the mayoral elections by Nir Barkat.
Also Thursday, the remand of another former Jerusalem deputy mayor, Eli Simchayof, has been extended by four days. He is also suspected of involvement in the Holyland affair.
Ronen Medzini contributed to this report