They had gone that night to the hospital. Her father was in intensive care, he might not make the night, they were told, his back injuries were that severe. He lasted four days.

In the months that followed, her mother had not hidden her anger at the service. Yet Gabriel had been drawn closer to the police. Her father’s best friend, Guy Longstock, a DI in counter terrorism, had encouraged her to consider a career in the force, and Gabriel had agreed, more to annoy her mother than honour her father. Longstock had stayed in touch, helping and advising her in her early days. And she had repaid the favour on that day when Jack Pearce fled the country on her watch for his new life in Syria as Abu Mujahid. Longstock was ancient by then, approaching retirement age, and was running an operation in the East End and urgently needed a surveillance unit. She agreed to his request and diverted the unit watching Pearce to help him out. She knew at the time that her decision was based more on loyalty to her father’s friend than reasoned judgement. In the inquiry, she had conceded it was a marginal call, but one that was defensible. But in her heart, in the darkest moments when she relived that day in her head, she knew she had made the wrong call.

#

Forty minutes later, Campbell slid the scene-of-crime report from the hotel across the table to Gabriel. Two or three dozen of the team had joined Gabriel and Skeffington in the small conference room. The mood was sombre.

‘The two men did a good job wiping the slate clean when they set fire to their hotel room,’ said Campbell. ‘But we got something all the same.’

‘From the room?’ said Gabriel.

‘Better than that, ma’am. The men threw four petrol bombs made from beer bottles. They were careful, but not careful enough because they didn’t use gloves. When you throw a petrol bomb, the glass breaks before the petrol ignites – so you can have quite chunky fragments lying around the place that haven’t been exposed to heat.’

‘Are you saying they got a fingerprint from a splinter of glass from an exploded petrol bomb?’ Skeffington’s eyebrows were raised. ‘You’re taking the mickey, Campbell?’

‘No, sir. Not fingerprints. But they did get DNA – most likely from skin or saliva.’

Gabriel whistled. ‘Could it be from the shopkeeper who sold them the beer?’ said Skeffington. ‘Or someone at the bottling plant.’

‘That’s what I wondered. But the SOCOs also got a sample from the door handle of the hotel room. That’s been harder to analyse – but they’ve found a match among the dozens of samples on the handle. They’re pretty confident it’s the same man. It’s gone through the national DNA database but come back as no trace. They’re trying a familial DNA analysis, ma’am. Just begun and should have the first results in twenty-four hours.’

Familial DNA searching was a relatively new field for the Met. Rather than looking for exact matches, a familial search looks for close matches – people with similar DNA who may be family members. Gabriel had used it a handful of times in the last few years. Each time, it had generated hundreds of potential suspects, and traditional police work was needed to whittle the shortlist down to something manageable.