Li had attended many autopsies over the years, but this was a procedure that was new to him. He watched, fascinated, as only a few minutes later the professor removed the frozen lung tissue from the freezer and transferred it, in its chuck, to the cutting area. Placing it hard against the blade, he turned the crank handle, drawing the sample across the cutting edge, for all the world like a ham slicer, cutting a wisp-thin section of tissue only microns thick, which was then touched to the surface of a room-temperature glass microscope slide. The sample instantly melted. The professor stained it with hematoxylin and eosin and handed it to Margaret for examination under the microscope.

“Microscopic examination of multiple sections of the lungs shows granulomata and multinucleated giant cells containing polarisable material.”

The process was repeated with the skin samples taken from the areas of needle track on the left foot. Margaret pushed her goggles up on to her forehead. “Same thing,” she said.

“Meaning what?” Li asked.

“Heroin users often grind up whatever other narcotics they can and inject the powder the way they do heroin. Particles of the pill residue get trapped in the tiny capillaries of the lungs and the surrounding lung tissue. Where the particles remain they get engulfed by inflammatory cells. There is clear evidence of that in this man’s lungs, as well as in the tracks in his foot.”

“So what does this tell us?”

“Nothing, except that he was probably a heroin user.”

“And cause of death?”

“As we all thought. Extensive thermal injury. Burning.”

“You said something about contusion, haemorrhaging, a fracture of the skull . . . What does all that mean?”

“It means someone hit him on the head with a blunt instrument. Not enough to kill him, but it would certainly have rendered him at least semiconscious, if not wholly unconscious.”

Li was startled. “It couldn’t have been accidental, or self-inflicted?”

She said dismissively, “Oh, I don’t think so. With an injury like that he’d have been in no condition to go walking around and setting himself up as a bonfire. And, as I understand it, he was found still in the lotus position. So he didn’t fall and hit his head on anything once he’d started burning. I believe he was knocked on the head and then sedated.” She paused. “Are you familiar with the term Special K?” Li frowned, clearly not. She smiled. “At least, that’s what they call it on the streets. A drug called ketamine. They used to use it as an anaesthetic induction agent in the States. Got some pretty nasty hallucinogenic side effects. My guess would be that when we get the blood tests back we’ll find he had been injected either with ketamine, or a very high dose of heroin. That would have made him more compliant and easier to handle.”

“You’re telling me he didn’t kill himself.” Li was stunned.