About 1,200 suspects are being investigated over their involvement in money laundering linked to vote-rigging in last year's Senate election, according to the Department of Special Investigation (DSI).
DSI spokesman Pol Maj Woranan Srilam said on Tuesday that the DSI and the Election Commission (EC) are jointly conducting the inquiry.
The DSI has been handling allegations of money laundering and the operation of an illegal secret organisation linked with the poll that was held in June last year, he said, adding the running of a body with unlawful income is an offence under the Anti-Money Laundering Act.
When money is acquired by such an organisation, it is deemed to be linked with money laundering practices, he said.
Pol Maj Woranan said the DSI will examine the financial trails of money and assets acquired through transactions before, during and after the latest Senate elections at the district, provincial and national levels.
Anyone who supported vote-rigging in the election will also face charges under Sections 5 and 9 of the Anti-Money Laundering Act, the spokesman said.
"An initial probe by the DSI has found that about 1,200 people are suspected of being involved in related financial transactions," he said.
The DSI will summon them to acknowledge the charges and hear their explanations, he added.
According to sources at the DSI, the agency will call in the first batch of suspects this month.
Pol Maj Woranan said the EC is focusing its probe on violations of the Senate election law and will determine if the suspects should be disqualified. It will also ask the Supreme Court to revoke their election rights.
He said the DSI will pursue criminal proceedings against wrongdoers on charges of money laundering and running an illegal secret organisation.
On May 9, the EC and the DSI jointly served summonses on six of 53 senators allegedly involved in the vote-rigging probe.
DSI director-general Pol Maj Yutthana Praedam confirmed EC officials had approved the first round and DSI officers had delivered them to the suspects' residences in Bangkok.
The six senators are Alongkot Vorakee, Chokchai Kittithanesuan, Jirasak Chookhwamdee, Pibulat Haruehanprakan, Wuttichart Kalyanamitra and Phisut Rattanawong.