The suspended chairman of the Economic and Financial Crimes Commission (EFCC) Abdulrasheed Bawa on Wednesday arrived at the facility of the Department of State Services.
The secret police invited him for questioning after his suspension was announced.
President Bola Tinubu suspended Bawa over alleged abuse of office and other “weighty allegations”.
Bawa began investigating Kogi State Governor Yahaya Bello despite the latter still occupying the governor’s seat.
Bello accused the EFCC led by Bawa of being a “pawn in the hands of political opponents in a bid to satisfy certain political interests.
The immediate past governor of Zamfara State Bello Matawalle in an interview with BBC Hausa in May accused Bawa of demanding a $2m bribe from him.
DSS spokesman Peter Afunanya said in a statement on Wednesday night that the invitation was on “investigative activities concerning him”.
The statement read, “The Department of State Services has invited Abdulrasheed Bawa, the suspended Chairman of the Economic and Financial Crimes Commission. Bawa arrived a few hours ago. The invitation relates to some investigative activities concerning him.”