‘I can do better than that, sir. I can show you.’

‘Where are you?’

‘Outside your front door.’

Collins heard Anderson emit a noise that was halfway between a grunt and a roar. She knew he wasn’t going to be happy to see her, but for once she didn’t care.

‘Give me a few minutes,’ muttered Anderson, before putting the phone down.

Ten minutes later Anderson opened the front door of his home and ushered Collins inside. They sat on opposite sides of his dining-room table, and Collins pushed a sheaf of papers across at him.

‘Let me get this straight,’ he said, leaning forward intently. ‘You’ve come here to tell me that Jessica Matthews’ – Anderson said the name slowly, each syllable heavy with sarcasm – ‘is a serial killer? Have you lost your mind?

‘Yesterday you were convinced the killer was Dr Bernard, one of the leading forensic psychologists in the world. Today it’s a top Home Office pathologist. Are you doing any actual police work or are you just working your way through Who’s Who?’

Collins moved a hand up to her hair and, realizing how unkempt it was, tried to smooth it down. ‘Okay, I know I sound crazy. I know I probably look crazy …’

‘You got that right. You’re seeing guilt everywhere. Are you sure you’re not just trying to find a suspect to fit the facts, instead of the other way around? You’ve got too many years in the job to make an error like that, surely.’

Collins shook her head. ‘But I also thought I was crazy when this idea first came to me. But it all fits. She has the right kind of background and the right level of knowledge. She fits the profile.’

Anderson tossed the papers back on the table. ‘Dozens of people fit the profile. That’s the way they’re put together. Deliberately vague. It doesn’t mean anything. Pretty much everyone on the team fits the profile. For crying out loud, I fit the profile! You’re going to need a lot more than that.’

‘There are errors in the autopsy, major omissions.’

Now it was Anderson’s turn to shake his head. ‘That’s the best you have? You might have misheard her. It could be nothing more than a simple mistake. She’s a highly respected doctor. She’s virtually part of the inquiry. She’s a close friend of half the senior staff down at Scotland Yard. Oh, and in case it’s somehow slipped your attention, she’s also female.’ He threw his hands high in the air in frustration. ‘Female serial killers are pretty much non-existent.’

‘They’re rare but not unheard of. Look at Rosemary West – ten murders over a period of sixteen years – or Myra Hindley – five murders. You’re making the classic mistake of dismissing her because she’s female.’

‘Yes, but in both those cases the women had male accomplices …’

‘And who’s to say that’s not the case with Matthews? There are things that she has said to me, things that have happened when we’ve been together.’

Anderson sat back and put his hands in his lap. ‘It’s all theory. Nothing concrete.’

‘There’s reasonable doubt.’

‘Not enough to make me want to touch this with a barge pole. It’s all very well when we’re dealing with the likes of a Billy-no-mates, of whom Billy Moorwood is a prime example. Spending a couple of days in a police cell makes precious little difference to his shitty life. For all we know it’s probably the highlight of his year.

‘But someone like Jessica Matthews. We can’t go around arresting people like that just because you’ve got some kind of stupid hunch about them.’ Anderson sat back in his chair and put the palms of his hands together, touching the tip of his nose with the tips of his fingers. ‘What I want are facts, not speculations. I can’t do anything based on theories pulled out of the air. You have to take into consideration all of the potential consequences of what you’re saying. Dr Jessica Matthews is one of the best pathologists there is. She’s been the lead examiner on literally hundreds of high-profile cases over the past few years. If we’re not a hundred per cent sure about this, the shit will really hit the fan.

‘Even if she’s cleared of any involvement in the murders after we’ve arrested her, the mud will stick to her name for years to come. Not only will she not be able to get any work but anyone who has ever been convicted on the basis of her evidence, anyone whose case file she’s even simply looked at, will have instant grounds for an appeal. We’re talking major, major disruption to the entire criminal justice system here. This needs to be entirely watertight. We can’t afford to fuck up, not even for a second.’

‘You’re right,’ snorted Collins. ‘You’re absolutely right. It’s much too big a risk. God knows what damage we might do to our careers if we carry on down this route. I’m sure Mrs Anderson would rather be the wife of a superintendent who played it safe than someone who actually cared about doing his job properly.’

A horrible silence hung in the air and Anderson narrowed his eyes for a moment. Then he snatched the papers out of Collins’s hand. He studied them carefully, his brow furled in concentration, while she stood up and paced impatiently back and forth in front of the dining table. At long last he looked up at her. ‘This part here, I don’t understand what I’m reading.’

Collins walked over to Anderson and he pointed at the paragraph he was reading.

‘It means she’s been giving us false information,’ said Collins. ‘I had Edward Larcombe take a look at one of the bodies. There are significant differences between the actual condition of the bodies when they arrived at the morgue and what she told me about them at the scene and during the autopsy.

‘Matthews told me it was possible the bodies had been frozen, that temperature readings were far below ambient. It’s true that the bodies must have been kept in cold storage – it’s the only way to explain the lack of decomposition – but by the time the bodies arrived at the morgue they had all thawed out. They were at room temperature and must have been for some time. There’s no way the bodies could have warmed up that fast.

‘And that’s just the start. There are dozens of other omissions. Needle sites not documented, toxicology results not passed on, details about the incisions not properly recorded. The only reason anyone would miss out that level of detail is to stop the finger of suspicion pointing back at them.’

‘Could just be mistakes, innocent mistakes,’ said Anderson.

‘She’s not that incompetent.’

‘So why lie? What was the point?’

‘She was playing games. Giving us a head start. ‘You have to remember what Dr Bernard said about the personality types who get involved in this type of crime. They are desperate to prove that they can outsmart the police. They want that level of confrontation. They want to be right there in the middle of the investigation. To some extent, they want to be suspects because they believe they’re clever enough to get away with it. That’s Jessica Matthews to a T.’

‘I don’t know, Collins. It’s a bit of a jump. We all take short cuts, we all makes mistakes with paperwork. If that alone were grounds for suspicion, half of MIT would be banged up by now.’

‘Even if you think that, we should at least talk to her, ask her about the anomalies in the autopsy reports.’

Anderson looked down at his watch. ‘Okay, let’s talk to her. There’s no harm in that. But let me do the talking. I don’t want to accuse her of anything just yet.’

‘And we should get Edward Larcombe to reexamine the bodies officially.’

‘Let’s not run before we can walk. One step at a time.’

Matthews did not answer the phone at her office; nor did she answer her mobile or the landline at her home. It took only a few more calls to establish that, despite having both an autopsy and a meeting scheduled for later that morning, Matthews had not been seen since the night before.