‘And,’ Barrett continued, ‘neither she nor Eddie had any knowledge of Robbie’s existence. She’s told us that in 1983 and four she knew her husband was having an affair. Apparently, she confronted her husband and said she would leave and take their small daughter with her unless he put an end to it. As far as Susan Kilpatrick is concerned that was the end of it. The dates do tie in and the DNA confirms it.’

‘Robbie grew up thinking his father abandoned him,’ Megaw said thoughtfully. ‘In fact, you are telling me that he didn’t know he existed.’

‘That’s about the sum of it, doctor,’ Palmer said.

‘This is a troubling development.’ Megaw scrunched his eyes up. ‘Do we know if Kilpatrick abused anyone else. His daughter perhaps?’

‘We’ve spoken to Marie Kilpatrick who denies her father ever laid a hand on her. I believe her, personally,’ Palmer said.

‘Abusers do tend to have a type. It’s uncommon for a paedophile to like boys and girls,’ the doctor informed them.

‘We are certain that Eddie did not know Robbie was his son.’

‘Well that’s something, I suppose.’ He paused. ‘I think knowledge of any of this could tip him right over the edge. My patient is unstable enough already. That revelation could be the final straw.’

‘Which is why we wanted to talk to you directly,’ Barrett cut in.

‘What would you like me to do, gentlemen?’ The doctor held his hands up.

‘You are his psychiatrist. We thought it might be better if it came from you.’

‘Does he really need to know?’ Megaw asked.

‘He has a half-sister,’ Palmer explained.

‘And this sister wants a relationship with him?’ The doctor did nothing to hide his scepticism.

‘No, she doesn’t. But she may come looking for answers one day.’

Doctor Megaw stood up and faced both men. ‘Gentlemen, I would request that you’d accompany me for a moment. There is something I think you should see.’

Palmer and Barrett looked at one another before getting up and following Megaw back along the corridor and up some stairs.

‘This is where we keep patients who have to be separated from the rest of the population.’ Megaw stumped up the stairs. ‘Robbie is being kept in isolation. He will be very groggy from the medication.’

‘Why did you separate him?’ Palmer asked as they continued to climb another level.

‘He became uncontrollably aggressive. He is a danger to the staff, other patients and himself.’

‘What sparked it off?’ Barrett wanted to know.