I was grateful for the chance to have a good ogle at Karen. As femmes fatales go, she was something of a let-down. Her best feature: long, glistening brown hair. Her face was several cheap tanning booths too teak, resembling a glazed bagel. Her tight black jeans and t-shirt served only to highlight her excess flesh, forcing it to spill out in the places she probably least wanted it to.

‘She reminds me of a busted bin bag,’ said Shep.

Her lifeless blue eyes conveyed a sullen insolence. When she spoke to her solicitor, she ended most sentences with a questioning, ‘you know?’ that implicitly granted her victim status. ‘This is the third time I’ve had to take time off work, you know? I can’t believe I have to go through it all again. It’s quite traumatic for me, you know?’

‘If the Foster family ever fall on hard times,’ piped up Shep, ‘they could charge people to slap her.’

The boys started on the afternoon of the murder: nothing too taxing. Karen parroted her original alibi: afternoon shopping in Blackheath with her sister Laura; she wore the same thing all day – jeans and her red Levi’s t-shirt; back to the Pines just after five p.m.; meeting Bethan Trott in the communal kitchen and heading to her room for tea and a soap opera; fish feeding with ‘Pete’ at six.

Problems verifying these events cropped up early. Karen and Laura didn’t buy anything in Blackheath, and she couldn’t remember any of the shops they’d visited.

Shep shook his head: ‘I mean, really, are you telling me a woman wouldn’t remember every shop she went into, on any shopping trip?’

Karen couldn’t recall being in her car outside the home at six p.m.: ‘I may have popped out to get cigarettes which I sometimes leave in the car, or a bottle of water.’

While helping to clean out the fish tanks, Karen developed an upset stomach. At about 7.45 p.m. she went to use the toilet and agreed to meet Peter by her car at eight p.m. She went back to her room to pick up her car keys and car park pass.

Almost inaudibly, she took up the story: ‘There weren’t any parking spaces on Sangora Road at that time of the night. So I parked on a street around the corner. I don’t know what it’s called. When we got to the house, Peter was surprised that the front door wasn’t double-locked. Marion always locked the mortise lock.’

‘And why did you go into the flat, Karen?’

‘My stomach still wasn’t right. I needed to use the toilet. I also wanted to say hello to Marion. We were good friends, you know?’

‘So you’re in the hallway of the house …’ prompted Colin.

‘He unlocked the door to the flat and went ahead of me up the stairs. When I heard him call out “Marion! Marion!” I ran upstairs. Pete felt Marion’s hand for a pulse and put his hand on her forehead. He said she was still lukewarm.

‘I felt for a pulse in Marion’s neck. I put my hand underneath her head and tried to lift her up. I told Pete that she was all stiff. I noticed Marion’s eyes were bloodshot and I saw cuts all over her dress. I saw blood around her mouth and ears. I started to scream. I must have gone into shock.’

She stopped, bowed her head and pushed her hair back with a trembling hand: rattled by grief or guilt, I couldn’t tell.

‘What was Pete doing?’

‘Pete didn’t touch her again. He said he was going downstairs to the neighbour’s flat to ring the police. I remembered seeing a police officer on the street as we were looking for a parking space. I ran outside to try to find him.’

‘That’s bullshit,’ I interjected, ‘we were the nearest cops. That’s why we got there first.’

Karen carried on: ‘I looked around but I couldn’t see him so I ran into the pub and told them to call the police because someone was dead. A few of the guys at the bar tried to calm me down and were asking me what had happened. I was hysterical.

‘Three or four people from the pub came with me back to the flat. They went upstairs to see what had happened and I followed them up. They looked at Marion, then went back downstairs.’

My heart sank; this explained all the prints on the doors.

I could barely hear Karen now. ‘Her skirt had risen up around her waist. I didn’t like people seeing her like that so I pulled it down and pushed her hair away from her face. I realised I had blood on my hands, so I went to the bathroom to wash them.’

Karen stopped for a quivering sob as Shep bucked in his seat.

‘I tell you what really troubles me here, Lynch,’ he ranted, ‘most people are instinctively wary of touching a dead body. It’s just not something civilians in that situation do. I mean, take Peter. He touched Marion’s hand and forehead. Once he knew she was dead, he didn’t touch her again. And he’s her husband. That might sound cold, but that’s the natural response.

‘What isn’t natural is Karen touching every part of the body, getting people in to trample the crime scene, washing her hands in the sink. The one place that she wouldn’t have been able to explain away her fingerprints would have been in the bathroom sink. She’d even thought of that, the crafty bitch. I’ll tell you what she was doing, Lynch. She was systematically contaminating the crime scene.’

Karen regained her composure. ‘Pete came back upstairs. He wanted to see if they’d been burgled. I followed him into the sitting room to check.’

Shep tutted: ‘Good old Pete. Wife dead on the landing, better check no one’s made off with the telly.’

‘Everything seemed normal and undisturbed. On my way back downstairs, I opened the window on the landing because I felt sick and wanted some fresh air. I remember the clasp on the window seemed loose.’

Shep shook his head: ‘While everyone else was in shock, she was busy destroying evidence and creating fake suspects.’

‘Okay, Karen, we want to move on to another area of interest now,’ said Mick.

Colin began. ‘What was the nature of your relationship with Peter Ryan?’

Karen bristled, ‘As I’ve said before, we’ve been working together for five years. We became friends. Then he met Marion and I became friends with both of them, you know?’

Colin went hunting through his papers, settled on one sheet and laid it carefully before him.

In a deadpan voice, he said: ‘On October 23rd, 1990, you listed the presents Pete had bought Marion for her birthday. At the bottom of the list, you wrote the words “sick, sick, sick”. Do you remember this, Karen? Would you like to see the piece of paper to confirm this is your writing?’

Karen’s bottom lip dropped slightly. I could sense her insides collapsing like cliffs into a raging sea.

‘What I want to know, Karen, is how you managed to listen to them in their room? Your room was four doors down the corridor.’

‘I had a key to Bethan’s room, which was next to theirs. I went in there to watch telly sometimes. I overheard them next door.’

‘You went in there to eavesdrop, to spy on them, didn’t you, Karen? You were obsessed with Peter Ryan. You wanted him all to yourself.’

She shook her head.

Colin raised his voice: ‘You told a witness that Peter was up to something behind Marion’s back. What was Peter up to, Karen?’

‘I don’t know what you’re talking about.’

‘Peter took Marion away for the weekend, but he wouldn’t even spend a night with you. Isn’t that what you said?’

‘I never said anything of the sort.’

‘Sex in a shed, Karen. That can’t be very comfortable.’

She remained stoically inscrutable.

‘We have a witness who saw you and Peter going at it in a shed at work last November. Must have been chilly too.’

Karen folded her arms, looked to one side and sighed petulantly.

‘You’re not denying it then, Karen? You admit having sex in the shed at work with Peter Ryan, last November?’

Karen’s gaze remained locked onto the side wall.

Good cop Mick interjected calmly.

‘Karen, we know you and Peter were having sex last year and that you used to go out together. There’s no point wasting our time here. So, why don’t you tell us, when did your sexual relationship with Pete begin?’