“A Triad hit-man, like my uncle suggested right at the outset. DNA on the blood inside the glove matches the DNA in the saliva on the cigarette ends. So there’s no doubt. He’s called Johnny Ren. And he walked into the headquarters of Section One this morning and stole my fob watch from my desk drawer.”

Margaret looked at him in astonishment. “How . . . ? Why?”

“I don’t know why.” Li was clearly agitated by it. “He’s been following us—you and me. Following our progress. He nearly killed me last night. And today he delivered a message. That he can do what he damn well likes and we can’t do anything about it.”

“You think that’s why he took your watch? To make a statement?”

Li shrugged. “Maybe. I don’t know. Maybe he’s just a mad bastard. But if he thinks we won’t get him, he’s wrong. By tomorrow morning his face will be as famous in China as Mao Zedong’s.”

They sat in silence for a moment, Margaret thinking quickly. “But he couldn’t have been responsible for blocking the AIDS test. Could he?”

Li shook his head. “No. That must either have been his employer or another employee.”

“Someone with a lot of clout, anyway,” Margaret said. “To subvert a pathologist and contrive to have the medical evidence destroyed.”

Li nodded solemnly, then turned to look at her. They had stopped at traffic lights. “I am beginning to have a bad feeling about it,” he said. “It is starting to look like your idea that Chao was burned to try to hide something might be closer to the truth after all. They just misjudged how much damage would be done by the fire.”

When they arrived at the Centre Professor Xie was in mid-autopsy. He looked up as the doors swung open, and Margaret saw colour rise on his face behind the mask. There was something close to panic in his eyes. But he remained outwardly cool, slipping off the mask and turning to his assistants, asking them to leave for a few minutes. Li waited until the door had closed behind them. “Do you still maintain, Professor, that Dr. Campbell did not ask you last night to arrange for a sample of Chao Heng’s blood to be AIDS-tested?”

The professor smiled nervously and glanced at Margaret. “No, of course not,” he said. “I’m sure Dr. Campbell did ask. But, you know, my English is not, perhaps, what it might be . . .”

“We never had any trouble with your English through three autopsies, Professor,” Margaret said. “And I didn’t have the impression last night that you in any way misunderstood my request. I’m sure Constable Lily Peng will bear me out.”

The colour drained from the professor’s face. Li said, “You are in deep trouble, Professor Xie. Attempting to destroy or cover up evidence would make you an accessory to murder.”