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.
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
Get Breaking news, live coverage, and Latest News from India and around the world on NDTV.com. Catch all the Live TV action on NDTV 24x7 and NDTV India. Like us on Facebook or follow us on Twitter and Instagram for latest news and live news updates.