According to a statement by the Federal Capital Territory (FCT) Command spokesman, Anjuguri Manzah, the arrest followed a preliminary probe by the criminal investigation department of the force.
The police added that the suspect whose identity was not revealed conspired with others, who are still at large, to carry out the crime.
The statement, also, warned members of the public to overlook inaccurate stories on social media about
the murder of Dagan so as not to pre-empt investigation.
47-year-old Dagan was killed by gunmen on Monday evening in her apartment in the Galadimawa District of Abuja.