Thumping her hand against the door, Kate called out, ‘Mr Brookes? It’s Detective Inspector Kate Matthews. Do you remember me?’

She pressed her ear closer to the door, straining to hear any movement inside. She looked back at Finn who was leaning against the staircase wall. She banged her hand again. ‘Mr Brookes?’

‘Seems like he’s not home.’ Finn shrugged.

The smell of fried onions drifted up the narrow staircase from the fried chicken takeaway below Brookes’s flat. It made Kate’s stomach grumble. At the top of the stairs, the small corridor to the left led to what had been Steph Graham’s one-bed studio flat, with the opposite corridor leading to her neighbour, Wallace Brookes. Kate made one more effort to reach Brookes, before signalling for Finn to head back downstairs. They exited and returned to the car.

‘Who is this Brookes guy?’ Finn asked when they were seated.

Kate opened the file she’d brought down. She thumbed through it until she found the image she was seeking, and showed Finn.

His eyes widened. ‘Jesus! Freaky-looking, isn’t he?’

Kate closed the folder and nodded. ‘We interviewed him the week following the discovery of Steph Graham’s body. He suffered with vitiligo, which meant his cells didn’t produce enough melanin to colour his skin. His face was as white as chalk, and there wasn’t a single hair follicle on the top of his head. His skin was hypersensitive to UV rays, and he had to cover himself if he ever left the property during the day. I remember we brought him in to take a witness statement a couple of days after we’d found her body. He wore this pale-yellow mac, with the collar turned up and a scarf around most of his face. It was only when we were safely inside a windowless interview room, with the lights dimmed, that he removed his scarf and spoke to us.’

Finn studied the image. ‘Why was he brought in?’

‘Under the premise he’d confirm Steph’s comings and goings from the flat; because of his condition he rarely went out during the day and was up for most of the night. You should have seen his place; windows covered with thick, dark card and blackout blinds, dimmed lights, no fresh air. The place reeked.’

‘You said the witness statement was a premise. Why did you really bring him in?’

‘Steph had made a complaint to her landlord about him a couple of months before her death.’

‘About?’

‘Something innocuous, from memory. Uh… she’d seen him lurking around, shadows of footsteps under the crack of her door or something. She thought he’d been listening at her door. He denied it, stating that he would have been asleep at that time of the day.’

‘You suspected him?’

‘I definitely felt there was something not quite right about him, but he had an alibi for the night of her murder.’

‘Which was?’

‘He runs an internet radio station from his flat, and he was talking on air from 10.00 p.m. until 3.00 a.m.’

‘That’s a long stint. Could he not have pre-recorded the show?’

‘We thought that, but a couple of people called in with requests and he was there to pick up.’

‘What about CCTV?’

‘The only street camera between here and the park where Steph was found wasn’t working. I had an officer review the footage we managed to pull from private cameras, but there was no sign of him. He had alibis on the nights of Willow and Roxie’s murders, too.’

‘Did you check to see if he was known to either of the first two victims?’

‘Yeah, we showed his picture to Willow’s parents, but neither of them recognised him. He has a face you would remember, so you wouldn’t have missed him if he’d been hanging around. We ran some background checks, just to be sure.’

‘So why the urgency to speak to him now?’

Kate pulled her phone from her pocket, unlocked it and slid it across the table.

Finn looked at the image on the screen. ‘Who’s this?’

Kate narrowed her eyes. ‘That’s Gavin Isbitt. Don’t you recognise him?’

Finn picked up the phone and studied the face again, the blood draining from his face. ‘Yes, that’s him: that’s the man who was in Amy’s flat.’

Kate returned the phone to her pocket. ‘Well, I’m hoping Wallace Brookes recognises him, too. I’ll leave a note under Brookes’s door and we’ll move on to Willow Daniels’ parents. I want to show them Isbitt’s face too.’