The suspended secretary to the government of the federation (SGF), Babachir Lawal, appeared before the investigative panel headed by Vice-President Yemi Osinbajo on Tuesday.
President Muhammadu Buhari set up the panel to probe Lawal and Ayo Oke, diirector-general of the National Intelligence Agency (NIA) who were suspended last week.
Lawal appeared before the committee over his indictment by a senate committee investigating the crisis in the north-east.
The senate committee had levelled allegations of misappropriation against the SGF.
Oke’s travails began after the Economic and Financial Crimes Commission (EFCC) raided an apartment in Ikoyi, Lagos.
The anti-graft agency discovered $43.4m, N23.2m and £27,800 at the apartment and Oke later said the monies belong to his agency.
On Monday, Oke appeared before the panel, which has Abubakar Malami, attorney-general of the federation and Babagana Munguno, national security adviser, as members.
Lawal Daura, director-general of the Department of State Services (DSS) and Ibrahim Magu, acting chairman of the EFCC, have also been questioned.
Critics of this administration have said nothing good will come out of the investigation.
The Ahmed Makarfi faction of the Peoples Democratic Party (PDP) had called on Buhari to set up a fresh committee, passing a vote of no confidence on the panel.