They moved on to the next door in silence. This bedroom was a mess. Bedding, tattered Barbie and My Little Pony magazines, an unopened Lego City box that, ironically, contained a building set for a prisoner transport, a jar of pink slime and a collection of Star Wars figures, along with some child-sized underwear.

Lilja turned to Klippan, who was standing right behind her. ‘You told me he doesn’t have children,’ she whispered and immediately realized what was going on.

‘He doesn’t.’

Klippan had clearly been correct in his assumption. Assar Skanås was not only a dyed-in-the-wool Nazi, he was a paedophile, too.

They returned to the corridor and continued to the next door, which had a sign on it depicting a peeing boy. Just like the other doors, this was closed but not locked. Unlike the other rooms, the light inside was clearly on.

On Lilja’s signal, they tore open the door and pushed into the empty bathroom, which didn’t look like it had been refurbished since the house was built.

But that was not what caught Lilja’s attention.

Nor was it the three-foot swastika on the wall next to the bath.

It was the faint sound of voices.

It sounded like children’s voices, two girls who had suddenly started talking to each other.

She turned to Klippan, who nodded for them to continue down the corridor. The further into the house they got, the more distinctly they could make out the voices. But they didn’t sound sad and there was no crying to be heard. On the contrary, they seemed excited and playful.

The corridor ended in a closed door with smoked glass panes through which you could only dimly make out what was happening on the other side. Lilja pushed the handle down. This door was locked, or maybe just stiff. She didn’t know and didn’t care; she raised her foot and kicked it in.

The sight that greeted her as she stormed into the living room with her gun at the ready was shocking, but with each throbbing of her pulse, her shock gave way to confusion. What she saw was two very young children, both girls, sitting naked on the floor, their legs spread wide, trying to put socks on their feet.

She had seen the same scene many times before. So many she’d lost count. When she was little, it had been one of her absolute favourite TV shows, and this particular episode, in which Madicken and her younger sister Lisabet sit naked on the floor getting dressed, she remembered as if she’d seen it yesterday.