Plain clothed and uniformed officers arrested two men and a woman in a car park at a Morrisons supermarket, in Darlington, on Tuesday afternoon.
The three, who were in their 30s and from Teesside, were arrested on suspicion of blackmailing a businessman from Darlington.
A second woman was arrested later in Brafferton, County Durham, on suspicion of conspiracy to blackmail.
The four are being held at three police stations around County Durham.
Durham Police officers seized documents and computer records from houses in the Grangetown area of Teesside and Brafferton village.
Det Supt Neil Malkin said the arrests marked the culmination of five days of intensive investigation.
^ Back to top | BBC Sport Home | BBC Homepage | Contact us | Help | ©