“Any evidence that the death wasn’t natural.”

“It wasn’t,” said Geung.

Mr. Geung, either under the influence of Siri and his spirits or through some innate Down syndrome sub-ability, had certain senses that reached into the realm of the dead. His intuition was rarely wrong.

They’d talked to Lah’s sons. The only existing condition they knew of was her insomnia and, for that, she’d been taking herbal magnolia bark for years. But they recalled that recently their mother had heard reports on Thai radio and had switched to pharmaceuticals. They didn’t know where she acquired them or how much she used. They gave Dtui all the drugs from their mother’s medicine cabinet in a plastic bag. There was nothing to be learned from the containers. Only one had a label and that was for heartburn powder. Another two or three pill boxes were unmarked and a large bottle with only a centimeter of liquid inside had a handwritten sticker that said: Two glasses before bed.

Siri recognized the pills in one of the boxes. China was flooding the market with its cheap versions of European drugs, and they made their products look as much like the originals as they could. The drug was a variety of benzodiazepine commonly prescribed for insomnia, and, in certain cases, for depression. By itself it presented no danger. With alcohol it could be fatal. But, according to the sons, their mother drank alcohol rarely and in moderation.

There were no obvious signs of drug abuse. In fact, as they foraged inside the bread lady, Dtui commented that the woman was in great shape internally. They took samples and Dtui and Geung retreated to the lab. The days of guesswork and comparative color-chart tests were behind them. The Soviets had funded a room with equipment and chemicals to test the fluids and flesh. Only Dtui could read the directions and instructions, and, without her, the room remained locked.

Siri sat under a tree with the chemistry lab goats and drank sweet coffee and ate sticky buns—the specialty of the Mahosot canteen—and waited for news.

“You were right about the benzodiazepine,” said Dtui. She sat beside the doctor on a pile of tractor tires. “High concentration but not enough to kill her.”

Mr. Geung joined them on the grass, greeting the goats by name.

“Anything else?” Siri asked.

“We don’t have results from blood and urine,” she said, “but we did an analysis on the contents of the bottle the boys gave us. Some sort of liquid morphine. Again, a high concentration and mixed with something sweet. I guess it was to take the taste away. Geung sampled it. He said it was like a milkshake.”

“Yummy,” said Geung.

“Lucky it wasn’t poison,” said Siri.