A woman, who the secret service accuse of using various false identities to gain access to Nigeria's presidential complex to run business scams, has been arrested.
The secret service said Amina Mohammed initially posed as Kogi state's first lady to gain entry to the presidential villa in the capital, Abuja.
She then allegedly invited people to the villa making them believe it was at the invitation of the president's wife.
At a press briefing about the arrest, Ms Mohammed shouted: "It is a lie."
Peter Afunanya, a spokesman for Nigeria's domestic spy agency, known as the Department of State Security, told reporters the scandal took place while First Lady Aisha Buhari was out of the country in November 2017.
Wealthy businessman Alexander Chika Okafor, invited to the presidential villa by Mohammed, accused her of defrauding him of 150 million naira (Sh42,421,188) over a property deal in the main city, Lagos, the secret service spokesman said.
Mohammed "took advantage of the fact that personalities such as first ladies, ministers and certain categories of officials are not taken through rigorous protocols and security checks at the villa posts", Mr Afunanya said.