Bitan’s first questioning took place on Sunday for over 13 hours.
Police rule out terrorism, investigating as criminal matter.
Police treating the explosion as a criminal incident, part of Israel's gang wars.
Alleged crime boss Michael Mor is among the detainees.
Undercover agent infiltrates dealers' network for over 5 months.
The arrest is part of the larger police investigation, termed “Case 1131,” into a number of mob-related murders. Police have filed 15 indictments in the case.
Among those arrested were people associated with the crime organization headed by Israeli mobster Ytizhak Abergil who currently sits in prison.
The detainees are suspected of involvement in the assassination of Avi David, shot at point-blank range outside a Bat Yam steakhouse in October 2011, among others.
HaTzel is associated with radical right wing groups and has an active social media presence by which he spreads his views, which have been criticized by many as racist and inciting.
Police recommend charging heads of Ramat Gan, Zichron Yaakov and Hatzor Haglilit.