Ms Josephine Kabura Irungu is currently being questioned by the Ethics and Anti-Corruption Commission (EACC) detectives over the Sh791 million National Youth Service scandal.
Ms Irungu is being grilled at the EACC headquarters over an affidavit she filed in court incriminating former Devolution Cabinet Secretary Anne Waiguru and other senior officials.
She arrived at Integrity Centre shortly after 10am accompanied by her lawyer, Mr Dennis Mosota.
Ms Irungu skipped a date with the EACC last Wednesday, with her lawyer saying she was unwell.
In her explosive affidavit, Ms Irungu accuses Ms Waiguru of masterminding the alleged Sh791 million theft.
She claims the former CS received a share of the money in question and played a key role in devising devious schemes to divert public attention and mislead investigative agencies from getting to the bottom of the scandal.
EACC spokesman Kairichi Marimba said the agency would reveal the next person to be grilled after Ms Irungu.
"We cannot reveal more about what they are telling detectives because we do not want to jeopardise investigations. Later on today (Tuesday) we will confirm who will be next," he said.
Ms Waiguru was grilled by EACC detectives for 10 hours Monday over issues raised in Ms Irungu’s affidavit.
Ms Waiguru has maintained her innocence and denied knowing Ms Irungu.
The former minister and her lawyers spent time poking holes in Ms Irungu's affidavit, which claimed Ms Waiguru played a role in the politically explosive scam in which the NYS lost millions in payouts to well-connected individuals and businessmen.
"The time she says I lived in Runda I actually stayed in Kitisuru," Ms Waiguru said, as she attempted to fight off a case that could derail her political ambitions.
Ms Waiguru has declared she would contest the Nairobi governorship, a move not well received by other players in the Jubilee coalition who have also set their eyes on the same seat in the coming elections.
She spent 10 hours at Integrity Centre fighting to clear her name in her second visit to the EACC headquarters.
Two weeks ago, the commission issued a discharge letter that appeared to clear her of involvement in the scam only for Ms Irungu to issue the explosive affidavit.