Treasury minister Henry Rotich finally left the Directorate of Criminal Investigations on Tuesday night, after about 12 hours of interrogation on the Sh21 billion Arror and Kimwarer dam scandals.
The Cabinet Secretary's lengthy closed-door grilling came as he honoured summons by DCI boss George Kinoti, who wants to look into 107 firms linked to the matter.
Reports indicated that Mr Rotich had been expected to answer questions on how the money was released to the Italian firm contracted to construct the dams, before the start of the project.
Mr Rotich's lawyer, Katwa Kigen, explained that the interrogation took long since there were matters that needed confirmation.
"We provided much of the clarification the interrogators wanted. It was a long process since there were issues that needed to be cross-checked and confirmed before submission," he sad.
The CS will still pay at least one more visit to the DCI headquarters for more questioning, Mr Kigen said, adding he will report back on Wednesday morning.
"There were documents we did not have, which we will return to the headquarters with," he said.
The minister left the DCI premises on Kiambu Road in Nairobi in a convoy of three vehicles.
CS Rotich is being probed for authorising of that amount of money to the two phantom dam projects in Elgeyo-Marakwet County.
He is also accused of writing to the National Land Commission asking officials to deal with land allocation issues to enable the Kerio Valley Development Authority to resettle residents displaced by the projects.