Today, Mr Dinakaran reached the Crime Branch Inter State Cell office around 2 pm.
Mr Dinakaran, the nephew of jailed AIADMK chief VK Sasikala, was questioned by an Assistant Commissioner of Police rank investigating officer.
A senior police official had said that Mr Dinakaran was given a questionnaire concerning the money trail, his association with Sukesh Chandrasekar - the middleman who was arrested - and whether he had met any Election Commission official.
Mr Dinakaran's call logs, WhatsApp messages and SMSes were also examined.
Mr Dinakaran is facing a rebellion in Chennai, as his faction of the party has decided that both Mr Dinakaran and his aunt, VK Sasikala, who is the party chief, would be evicted from their positions. That move is aimed at facilitating a merger with a rival, though much smaller faction of the AIADMK, led by former Chief Minister O Panneerselvam.
A few days ago he chose to step aside from the party following a revolt against him by all ministers with the Chief Minister's backing.
With inputs from agencies