During the interrogation that spanned six hours, Shaji denied the charges against him.
The developments also generated debates on groupism in IUML and corrupt deals of its leaders.
A court in November last had ordered a Vigilance probe against the Azhikode MLA on allegations that he amassed assets disproportionate to his known sources of income.
The 49-year-old MLA underwent an angioplasty and his condition is stated to be stable. In the Covid test which was conducted before treatment, Shaji tested positive.
Sleuths will soon record statements of Chennithala and former UDF ministers V S Sivakumar and K Babu, sources said.