As she was approaching her car, Jessica took her phone out to turn the volume back up having muted it for the visit. She had a few unimportant emails but also a missed call and another text message from Adam. She thought about deleting it but out of pure curiosity she clicked to open it.

‘Call me pls. Urgent. Not abt us.’

Jessica had reached the car but didn’t open the door to get in. She didn’t particularly want to talk to him but the way he had worded the message was different to the others he had sent. Jessica ducked to look through the car’s window and catch Cole’s eye. She pointed to her phone to let him know she had to make a call. He nodded and she turned around, leaning back on the car before dialling Adam’s number.

He answered after one ring. ‘Hello?’

‘Hi, Adam.’

‘Oh God, look, um, thanks for calling.’ Jessica hoped she hadn’t been duped into contacting him for personal reasons. She knew it was all her fault but couldn’t face things just yet. He soon told her the reason for calling. ‘I’ve not told my boss yet, Jess, but I think I’ve got something. I’ve tested and re-tested all morning. I think Donald McKenna has a sister.’

29

Jessica felt an enormous sense of familiarity as it had only been a day ago she’d had a phone conversation where she couldn’t quite take in what she was being told. ‘I’m sorry, what?’

‘A sister. I know there’s nothing in his birth records or anything like that but there’s something not right here.’

‘Are you at Bradford Park?’

‘Yes.’

‘We’re coming over.’ Jessica hung up and quickly got in the car, telling Cole they had to go to the laboratories. When he asked why, she said she wasn’t completely sure but something big was happening.

She knew from experience the inspector was a steady driver but tried to stay patient during the journey across the city. Jessica had seen the records herself which all said Donald McKenna was an only child. An officer had even photocopied his birth certificate and related family documents from the local register office and they knew there were no other known relatives. The idea of him having a sister was barely believable.

Eventually they pulled into the labs’ car park and Jessica made for reception, Cole lagging behind. Her haste didn’t do her any good as they had to wait for someone to lead them through to the lab areas anyway. They were greeted by a woman Jessica didn’t know and Adam, who nervously kept his eyes on the floor. She introduced herself as the head scientist for the facility and knew Jessica because they had talked on the phone. She led them into a small office where the four of them sat around a table.

‘I know why you’re here,’ the woman said, ‘but I should tell you we don’t have one hundred per cent confirmation for you yet. I think Adam should be able to fill you in.’

Adam looked at Cole and his boss but refused to acknowledge Jessica. She didn’t blame him but hung on everything he said. ‘We had a routine request come in this morning from the Avon and Somerset Police force. They arrested a woman in Bristol last week on suspicion of grievous bodily harm. Because of the severity of the incident she was remanded but in the meantime they logged her swab onto the National DNA Database. That’s all completely normal but what happens on the system is that it links together family members.’

His boss cut in. ‘The reason it does that is if we go to a scene and get a blood sample or something like that, we might not find an exact match for it in the database because the person has no criminal record. But we could end up with something like a fifty per cent match which would indicate the culprit was a parent or sibling of someone we already had registered.’

‘That’s pretty clever,’ Cole said. ‘So even if you don’t have the person on your system you can tell if they’re related?’

‘Right,’ said the woman. ‘Sorry, Adam, you tell them.’ Jessica said nothing, eagerly waiting to hear what they had found.

‘After they logged the DNA, it gave them a quarter match to Donald McKenna, which might mean this woman was his half-sister or aunt or niece or something like that. Because Mr McKenna has no known relatives, they called this morning to say it looked like there might be a mistake on the system. It wouldn’t usually happen but an error like that would be so rare the guy down there thought he would check.’

The female scientist cut in again. ‘With the notoriety of McKenna at the moment, Adam did a full retest on the sample and passed it back through to the Bristol labs where they confirmed it. This woman is definitely related to him.’

‘Do we know how?’ Jessica asked.

‘I don’t want to baffle you all with science but we check something called “mitochondrial DNA”,’ the woman said. ‘This is only inherited from your mother and is how you can follow a family line backwards. Through looking at that, we know McKenna and the woman in Bristol are half-siblings and have the same mother but different fathers.’

‘Does that mean this woman could be responsible for the murders up here?’ Jessica asked.

‘No, it’s not as simple as that,’ the lab manager answered. ‘We know this woman is related but, at the same time, her sample is still different to her half-brother’s. It’s only a partial match.’

‘Has anyone told this woman or asked her if she knows McKenna?’ Cole asked.

‘I can’t tell you if she already knows but, from our end, the only people aware are us and the Bristol lab.’

‘Good work,’ Jessica said.

‘It’s Adam you should thank,’ his boss replied. ‘He was the one who spotted it. We have one final round of testing to do but you’ll have confirmation one way or the other by the end of the day.’

Adam kept his head down as Cole congratulated him and Jessica made sure she spoke at the exact same time as her boss so her words would be drowned out.

‘While we’re here,’ Jessica said, ‘is this where McKenna’s phone was brought?’

‘Yes and no,’ replied the female scientist. ‘It is this building but on a different floor. I can take you up if you want?’

Jessica was relieved that Adam stayed behind as the woman led them upstairs towards a department that worked with electronics. They didn’t get anything new from the people who had been testing the phone though. The expert said they had only been able to extract the numbers that had been stored in the phone book, which they already had. As far as they could tell it had never called a different number, had never received a call and no text messages had either been sent or opened.

Pretty much the only thing it did tell them was that, whatever was happening, it was likely McKenna was calling the shots in one way or another as people weren’t calling him, he was phoning them.

Back at the station, Jessica was looking forward to telling Farraday what had happened. Cole did the speaking but Jessica didn’t take her eyes from the DCI. She wondered if he already knew about McKenna’s sister and if she was somehow connected to everything that was going on. If he did know, or if he was surprised, he showed no emotion at all.

Having already spent large parts of one day on a train to Wales that week, Jessica had another journey to Bristol, this time with Cole. Neither of them were big on small talk and Jessica spent the trip flicking through a magazine and reading Internet sites on her phone. She had half-expected either Adam or Dennis to message her the night before but there had been no contact. For the second evening running she felt confident enough not to watch the chief inspector’s house and had another uninterrupted night of sleep.

After their train arrived at the station, they caught a taxi from the rank outside but the driver didn’t know where he was going. Jessica checked the papers she had printed out the night before and told him the prison they were looking for was next to a village called ‘Falfield’ north of the city.