‘Them too. And get someone to double-check with her family which parks those photographs were taken in. We’re only interested in those in or around Edinburgh.’ She grabbed her laptop and began clicking and scrolling.

‘But everyone with children or dogs has taken photographs in parks. It has to be one of the most common threads in family images.’

‘Exactly,’ Connie said. ‘Look. Angela has these photos on her walls.’ She pointed at images from the Fernycrofts’ house. The park was a focal point.

‘That still doesn’t link it to Meggy’s disappearance. I may not be a profiler, but even I’m aware that offenders shifting victim type to such a vast degree is highly unusual.’

‘Yup.’

‘You don’t think we should talk about that before we alert Police Scotland to the fact that a predator might be lurking in their green spaces? Because that’s not so much a profile as an invitation to every would-be vigilante to start beating up any single male seen on parkland within a hundred-mile radius.’

‘Okay,’ she said, putting her laptop aside. ‘You’re a predator looking for a particular type of woman. Someone with youngish children. Where do you go to find her?’

‘School playground?’

‘Now limit the parameters. You don’t just want a mom who drops off and picks up the kids, you want that extra-special mother. You want to witness parental engagement. You probably want to be able to do more than just imagine what she’s saying to her kids. That requires being able to get close enough without standing out.’

‘Could be done in a number of different places. Shops, restaurants, even on the street.’

‘That’s generic. The conversations will all be the same. What shall we put in the shopping cart for dinner? Are we running late? You’re looking for somewhere where the mother can let her guard down, where she has the chance to showcase her parenting skills.’

‘You mean … is she actively playing with her children, or sitting on a park bench checking her social media?’

‘Exactly,’ Connie said. ‘A park is an underrated arena for assessing relationships. Teenagers go there either for headspace or to cause trouble. Elderly people who live alone might go there hoping for a chat with a passerby. Parents go there because it provides exercise and a chance for play, but playing with kids is hard work. It requires imaginative and physical effort. Swimming pools are the other place where the same is true.’

‘Except at a pool there would be a higher likelihood of cameras,’ Baarda said. ‘But Meggy’s twelve years old. Angela and Elspeth are both in their thirties. You said yourself there had to be some sort of psychosexual motivation to those crimes. Meggy wouldn’t fit his type.’