In addition to binding specificity, the other key feature of an immunoassay is that the test produces a measurable signal in response to a particular antigen-antibody hookup. In the case of ricin, a green light is given off. That’s the chromatographic part of the long term.

The green light is measured by a spectrophotometer or similar piece of equipment. Basically, the brighter the glow, the more ricin there is in a sample.

Larabee nodded.

“That explains the fast turnaround time,” I said.

In the past few years immunoassay testing has become quick and simple. There are now kits for the detection of ricin, anthrax, plague, tularemia, and many other biotoxins.

“But it doesn’t explain how ricin got into our John Doe,” Larabee said.

“That’s the stuff that killed Georgi Markov.” I referred to a Bulgarian journalist murdered in London in 1978.

“I doubt our John Doe was ass-stabbed with an umbrella.” “Markov was jabbed in the leg,” I said.

Larabee gave me a look.

I thought a moment. If ingested, inhaled, or injected, ricin causes nausea, muscle spasm, severe diarrhea, convulsion, coma, and ultimately, death.

“Ricin poisoning would fit your autopsy finding,” I said.

“And would explain the interest of the feds.” The phone rang. Larabee ignored it. “The military has been studying ricin for years. They’ve tried coating bullets and artillery rounds with it. They’ve tested it in cluster bombs. I did a quick check after this thing came in.”

He flapped a hand at the fax. “Ricin is listed as a schedule-one controlled substance under both the 1972 Biological Weapons Convention and the 1997 Chemical Weapons Convention.”

“But other toxins are much more effective bioweapons. Anthrax, for example. You’d need tons of ricin compared to a kilo of anthrax.” I’d read that somewhere. “And ricin breaks down relatively quickly. Anthrax spores can remain lethal for decades.”

“The average person can’t lay his hands on anthrax. Or botulin. Or tetanus. The castor bean plant is a friggin’ ornamental. Any loon can grow it in his garden.”

I started to comment. Larabee wasn’t finished.

“Close to a million tons of castor beans are processed every year. About five percent of that ends up as waste containing high concentrations of ricin.”

“So how’d our John Doe die of ricin poisoning?” I asked.

“And end up in a barrel of asphalt in a landfill in Concord?”

“And where the hell is he?”

Without a word, Larabee put his desk phone on speaker and jabbed the buttons. Ten beeps, a buzzy ring, then Hawkins’s voice answered.

“Can’t survive without me, eh, Doc?”

“Sorry to bother you on your day off.” Taut.

“No bother.”

“This may sound odd. But we can’t find the body from the landfill.”

There was no response. In the background I could hear the cadence of a televised baseball game.

“You there?”

“I’m here. Just trying to figure the question.”

“MCME 227-11. The man in the asphalt.”