Murder squad detectives in Cambridgeshire have arrested two people they were trying to trace after a body was discovered in a ditch by the A16 near Peterborough on Saturday.
Gary Stretch and Joanna Dennehy are now helping police with their enquiries.
Two people are being questioned in relation to the deaths of three men near Peterborough.
Police have searched a house in Cambridgeshire which is at the centre of a triple murder enquiry.
Cambridgeshire police are investigating the murders of three men in the Peterborough area.