Detective Colin Barnard spent a lot of time concentrating on the case, for his boss DCI Eden. Upon undertaking a DNA siblings test, he eventually established that Raymond Foster i.e. Clive Manning, had quite a few illegitimate children in the Harold Hill, Essex area. Along with proving he was the Father of Susan Darcy's son Michael. Although there was nothing on record of Michael, of where he was, or if in fact he was still alive.
He further proved that a third persons DNA taken from the bodies of Susan Darcy and Raymond Foster was the same. Not a lot but enough to make a positive connection.
On Susan's body, there was one single hair. While on Mr Foster the DNA had been taken from a couple of beads of sweat that might have dropped on the body as the murderer tried to drag it behind the settee. To hide it from view as people entered the room. Thus, assuming the room to be empty.
Try as they might they could not make a connection. The DNA was not even on the National data base system, which further informed the authorities that the killer was not connected with any other known crime in the country. From here the trail was cold. The problem now was who was that person, and where was Michael Darcy.