“Down five flights? This guy must have been pretty fit. But let’s not get ahead of ourselves. He could have spent up to two hours in the apartment, right? Would he not have left some trace? Had a coffee, gone for a pee, smoked a cigarette?”

Li shrugged. “My guess is he would wear gloves. He wouldn’t have a coffee or a cigarette, because he’s a professional. If he had a pee, it’s long gone.”

“I’d still like to look around,” Margaret said.

They spent nearly fifteen minutes going through the apartment room by room, finding nothing, before finally entering the bathroom. It was as dirty as Li remembered it. The creams and ointments in half-squeezed tubes, the bloodstained safety razor, the spattered mirror above the sink. The used towels still lay over the side of the bath, but were dry now. Margaret opened the bathroom cabinet. “Jesus,” she said, and lifted out the plastic tubs and bottles of pills. She looked at Li. “Do you know what this stuff is?”

He shook his head. “The man was sick.”

“He sure was.” She rattled a bottle at him. “Epivir. Or 3TC as it’s known. A reverse transcriptase inhibitor. You know what that is?”

“No idea.”

“Reverse transcriptase is an enzyme that helps replicate DNA.” She shook one of the plastic tubs and the pills inside rattled like dried beans. “Crixivan. A protease inhibitor, another enzyme involved in replication.” She picked up another bottle. “And AZT. Well, there’s hardly anyone in the West who hasn’t heard of that.”

He was still in the dark.

“Taken simultaneously, these three comprise the triple drug therapy that’s now being used to combat HIV. They act to prevent the virus from replicating.” She paused. “Looks like our friend Mr. Chao had AIDS.”

The elevator man watched them with the same intense curiosity on the way down as he had on the way up. He was irritated by the fact that they were speaking English and he had no idea what they were saying.

In his mind, Li was warming to Margaret’s idea that Chao had been burned to try to hide something. “Do you think,” he said, “that Chao could have been set on fire to try and disguise the fact that he had AIDS?”

Margaret didn’t. She used the same reasoning Li had earlier to dismiss her initial idea. “If he was, they didn’t do a very good job. He’d need to have been really fried for us not to be able to get blood or tissue samples to test for it. Anyway, you never routinely test for AIDS during autopsy, not without a reason. And they left his medicines in the bathroom cabinet. Bit of a giveaway. But more than any of that, why would they? Why would anyone have any interest in trying to hide the fact that Chao Heng had AIDS?”