Appointment of Inspector-General and control of Nigeria Police Force
Section 215(2) · 1999 Constitution (2004 edition)
What Constitution says
(2) The Nigeria Police Force shall be under the command of the Inspector-General of Police and contingents of the Nigeria Police Force stationed in a state shall, subject to the authority of the Inspector-General of Police, be under the command of the Commissioner of Police of that state.
This is the 1999 Constitution as published in 2004. Later amendments aren't included yet, so a section may have changed since.
Original source
Official Gazette · CFRN 1999 official PDF · printed page 96. Original document
Release: draft-c8d50d87fae9. Source scope, review and corrections