A group of 30 senators will file a complaint with the National Anti-Corruption Commission (NACC) against Justice Minister Pol Col Tawee Sodsong and Department of Special Investigation (DSI) director-general Pol Maj Yutthana Praedam on Wednesday for negligence of duty under Section 157 of the Criminal Code.
The complaints will be made following a March 6 decision by the DSI's special cases board to investigate money-laundering allegations related to the latest Senate election.
The board is chaired by Deputy Prime Minister Phumtham Wechayachai. Its decision was later questioned by Senator Chatwat Saengpetch.
Mr Chatwat, who is among the 30 senators who will file the complaint, said the DSI was able to forward related evidence to the Election Commission (EC) in late February but it did not do so. Later, the DSI accused the EC of prevaricating.
"Was the DSI under any kind of political influence? Or was its intention to intimidate?" Mr Chatwat asked.
The DSI falls under the command of the Justice Ministry.
Political observers have largely viewed complaints related to the Senate election as being politically motivated — a tit-for-tat between political factions.
However, Mr Chatwat said that he, as chair of the Senate committee on constitutional organisations, anti-corruption and good governance, was simply following protocol.
Meanwhile, Pol Col Tawee said, in response to the latest complaint, that he did not think the move was political.
He said the investigation into the money trail related to some 7,000 people has begun. Forensic evidence would prove whether there was collusion in the Senate election process, he added.
"We are not bullying or helping anyone. We only want the facts and justice to speak for themselves," said the justice minister.
Pol Col Tawee added that the names he had received, which were involved in the alleged collusion, matched those of 138 senators. However, no specific allegations have yet been made against any of them.
Pol Col Tawee also brushed aside other complaints against him, including his purported role in facilitating former prime minister Thaksin Shinawatra's stay in the Police General Hospital, instead of serving his term in prison, upon his return from exile overseas.