Eastwood Park Prison was about as different to Manchester’s as Jessica could have imagined. The one in the north handled 1,300 of the most serious male offenders with the one McKenna’s half-sister was at holding 350 lower-risk females. Strangeways was full of heavy metal doors and cells that stretched three storeys high but the building Jessica and Cole were shown into had a mixture of one- and two-storey rooms and everything was decorated in more delicate cream and red colours.

Back at Manchester, even when the wing had been cleared for her to look at McKenna’s cell, Jessica had felt an air of menace that wasn’t present at the women’s prison. She didn’t doubt there were still plenty of unsavoury things that went on behind closed doors but thought the atmosphere was more geared towards education and rehabilitation than it was where McKenna was based.

The governor greeted them both at the entrance of the prison and was far cheerier than the one at Strangeways. The previous evening, Cole had established the prisoner’s name was Mary O’Connor and spoke to the governor, assuring him the woman wasn’t suspected of any further crime but that they wanted to speak to her as a potential witness.

On arrival, they first went to the governor’s office where they explained to him their situation and said there was a good chance Mary might not know she had a brother. It was good practice given as the man’s staff would have to deal with the prisoner once they had left.

He led them through to an empty visiting room and Mary O’Connor was brought through uncuffed and sat opposite them. Two prison guards stood close enough to act if there were any problems but far enough away so they weren’t in earshot. Jessica introduced herself and DI Cole and explained they had travelled down from Manchester to see her.

The woman had long black hair with grey strands around her ears. Facially she wasn’t similar to McKenna but Jessica could see her light blue eyes were identical; they must have inherited them from their mother. The colour seemed familiar to Jessica in another way too but she couldn’t place them.

Jessica checked the woman’s name and then her age. ‘What I’ve got to say may or may not come as a shock to you, Mary,’ Jessica said. ‘But do you know you have a brother?’

The woman smiled at them. ‘Not me, you must be thinking of another Mary O’Connor. I was brought up on my own and my ma and dad died years ago.’

‘I’m sorry, Mary, but we’re not telling you this because of your name, it’s because of the mouth swab you gave when you were arrested. I don’t want to make it too complicated but basically that sample was matched to someone else in prison and it shows you’re related as you have the same mother.’

Mary’s smile had begun to slip as Jessica spoke and her expression was now a look of pure puzzlement. She had an accent that was hard to place. There was definitely a twinge of Irish but something from the local area too. ‘Is he younger or older than me?’

‘Younger by a couple of years.’

‘See, that’s why it must be a mistake. My ma couldn’t have children after me. She always told me they wanted to have a big family but there was some medical problem so I ended up on my own.’

‘I can’t tell you whether what you were told was right or not, Mary, but these tests aren’t wrong. I know it’s a bit scientific but we brought these papers down for you.’

Jessica reached into an envelope and pushed some sheets across the table. She had looked over them herself on the train. The language wasn’t the clearest but even from the graphics you could see that whatever it was displaying matched the other part. ‘I’m sorry, I don’t read well,’ the woman said. Jessica told Mary the man’s name was Donald McKenna and did her best to show her the parts of the chart she should be looking at but felt hampered as she wasn’t completely certain either.

The woman rubbed her head and grimaced. ‘If this is right, what are you saying? That my mum is his mum?’

‘Well, that’s partly why we’re here, we don’t know. We have a copy of Mr McKenna’s birth certificate and wondered if we could compare it to yours?’

‘You’ll do well, I’ve never had one.’

Jessica looked to Cole and back again. ‘How is that possible?’

‘My ma and dad were travellers and we moved around a lot. There was always some kind of work. Usually you’d get married in the community but they died before I was an adult and it wasn’t the life for me. I ended up settling around this area.’

‘But how did you get work, a passport or driving licence?’

‘Never had a passport or driving licence but I did get a national insurance number. I don’t know if it’s easier now but I got passed from agency to agency back then. Event ually someone was given my case and sorted it out. They told me it’s not completely uncommon for traveller children to be unregistered and reckoned they get three or four every year. It didn’t stop them arsing me about for a couple of years but I ended up with a number that lets me work. I still don’t have a birth certificate though.’

Mary looked as if it was a story she was familiar with telling. Given the employers, councils and other organisations that would have asked the question over the years, it wasn’t surprising.

‘That’s mad,’ Jessica said.

‘You’re telling me. I’ve had to put up with this all my life.’

A possibility was occurring to Jessica. ‘Mary, can I ask you something personal?’

The woman looked back at her. ‘I think you’re going to ask me something I’ve had in the back of my mind for the past fifty-odd years.’

‘Do you think there’s a chance your parents weren’t actually your parents?’

Tears suddenly formed in the prisoner’s eyes and Jessica felt guilty for asking it. Given she was locked up, Mary was about as calm an inmate as Jessica had ever met. She found herself wondering how on earth this mild person in front of her had assaulted someone seriously enough to end up here. Jessica motioned for one of the guards, who picked up some tissues from one of the other tables and brought them over. Mary took one and blew her nose. ‘I guess it would answer a lot of questions,’ she finally said through the tears.

‘The problem is, Mary, that Mr McKenna’s mother has also passed away and there’s no father listed on his birth certificate. Without your parents, the way I understand it is that we have no way of knowing whether you and he shared “your” mother or “his” mother. All we know is that you definitely had different fathers. Your dad could well still be your own.’

‘So you’re saying that, one way or the other, either my ma or my dad was definitely not mine? Either my dad went with his ma or my ma went with someone else?’

Jessica took a deep breath, trying not to look confused. ‘I think so, yes. I’m sorry.’

The woman had tears in her eyes again. ‘Does my brother know?’

‘Not yet, no.’

‘Why is he in prison?’

‘An armed robbery. He’s serving life.’

Mary looked down at herself and flung her arm into the air. ‘I guess we have something in common straight away. It must run in the family.’ Jessica said nothing. The woman carried on sniffing. ‘Do you think there’s any way they would let us meet?’

Jessica felt out of her depth, not knowing the answer. ‘I don’t know how these things work. You’re on remand here, I guess some of it depends on what happens at your trial.’

The woman leant back on her seat, wiping away more tears. ‘Not gonna be a trial, m’dear. I’m pleading guilty.’

With little more they could get from the woman, they said their goodbyes and one of the prison officers gave them a lift back to the train station.

When they were back on the train, they sat opposite each other, speaking quietly to avoid being overheard, aware it was unlikely to do any harm but feeling concerned for the woman’s privacy.

‘What do you reckon?’ Cole asked.