Babachir Lawal, former secretary to the government of the federation, is currently in the custody of the Economic and Financial Crimes Commission (EFCC).
The EFCC Acting Head of Media and Publicity, Mr Samin Amaddin, confirmed this to Channels Television on Wednesday.
Mr Amaddin said the former SGF is cooperating with investigators and has been making useful statements.
He added that his interview with the anti-corruption agency would continue on Thursday.
A source who prefers not to be named said Lawal arrived at the commission’s headquarters in Abuja around 11am, after which he was interrogated.
The source said the former top official in the administration of President Muhammadu Buhari would spend the night in the office of the anti-graft agency and his interview with the officials would continue around 11am on Thursday.
The development comes 24 hours after ex-President Olusegun Obasanjo accused Buhari of shielding his corrupt allies.
Lawal’s travails began on December 14, 2016, when the senate ad-hoc committee on ‘mounting humanitarian crisis in the north-east’ indicted him of fraud in a contract awarded for the clearing of “invasive plant species” in Yobe state, through the Presidential Initiative on Northeast (PINE).
PINE, which was under Lawal, was at the time unable to account for N2.5 billion allocated to it for the alleviation of the IDPs’ suffering.
Lawal’s crime, according to the ad-hoc committee, included his alleged spending of N570m to cut grass.
Rholavision Engineering Ltd, a company owned by him, was also said to have got suspicious payments of N200m from the contract.
Rholavision’s bank statements and other documents obtained by TheCable at the time had shown how Josmon Technologies Ltd, a company that got the contract from PINE to clear grass for N248, 939, 231, made cash deposits of N10m into Lawal’s company’s account 20 times from March 29.
Although the former SGF had claimed that he resigned from his company on August 15, 2015, and as a result was not a party to whatever business it contracted, TheCable had also confirmed from a document from the Corporate Affairs Commission (CAC) that he was a director of Rholavision until September 16, 2016, when he wrote to the commission informing it of his intention to relinquish 1,500,000 ordinary shares.
After sacking him in October, Buhari said he expected anti-graft agencies to go after him.