And there was a silence around the table as each of them considered what exactly that might mean. They all knew there was a history between Li and The Needle. Li had managed to obtain a warrant for his arrest three years ago. And then the only witness in the case had turned his bicycle under the wheels of a No. 4 trolley bus on Wangfujing Street. It had been impossible to prove it was anything other than an accident, and The Needle had walked.

There had been a time when men like The Needle would have been “persuaded” to confess to their crimes, and punished accordingly. But times had changed. Police practice, and the whole justice system, was under close scrutiny. And conventional means of applying social pressures on an individual, through his work unit, did not apply to entrepreneurs like The Needle, who would claim that his income came from the covered market stalls he ran in Liulichangxi Street.

The meeting ended in the same gloomy mood in which it had begun. Beyond continuing the interviews and taking statements from potential witnesses, no one had any fresh ideas. But as they drifted out of the meeting room, there was a buzz among the detectives, a sense of anticipation about Li’s intention to beard The Needle in his own den.

IV

Li parked at the door of the Centre of Material Evidence Determination and went inside. In Professor Xie’s outer office he found Lily Peng sitting with a face like sour cream, flipping agitatedly through a science magazine. “Is Dr. Campbell here?” he asked.

She flicked a thumb towards the autopsy suite. “In there. For hours.”

“Not watching today?” he asked, with a flicker of a smile.

She glared at him. “No room,” she said.

He frowned, puzzled. “What do you mean?”

“See for yourself.” And she turned back to her magazine.

Li pushed through two sets of swing-doors into the autopsy suite, and found it crowded with fifteen students in green coats and face masks gathered round the gaping body of the itinerant worker from Shanghai. The chest cavity was still exposed, the scalp peeled down over the face, and the brain had been removed from the skull. Some of the faces of the students were the same colour as their coats. Two autopsy assistants were in the process of tidying up the corpse. Margaret was giving a running commentary.