Ian

Chapter 48

Face wet with tears, Nazihah Alhabi clung tightly to her baby. Her husband's cousin Fariq Yusef tried to be of comfort, as she was faced by questions from Kate and Castle. Kate did her best to be gentle. She leaned forward in her chair, resting her forearms on her thighs. "Mrs. Alhabi, your husband had information someone wanted, wanted enough to kill him for it. Have you any idea what that might have been or who would have wanted it?"

Fresh sobs erupted from Nazihah's chest. "It makes no sense, not here, not in the United States. Amir drove a cab. He knew nothing worth killing for."

"Mrs. Alhabi," Castle put in, "you said not here. Would he have had information elsewhere, perhaps in your native country?"

"In Syria, Amir was an engineer," Fariq explained. "He studied hard and he learned, because he wanted to move our country forward, make it a better place for our people. But he was forced into building weapons. That's why we left. That's why we were given asylum. He wanted no part of that here."

"Nuclear weapons?" Castle queried.

Fariq shook his head. "We don't know. Amir thought it would be better if we didn't."

"So is it possible," Kate questioned, "that someone could have tried to avail themselves of his expertise?"

"Amir would never have given in to anything like that," Nazihah insisted. He gave up everything he was, almost everything we had, to avoid being part of that kind of destruction."

"And I'm sure he didn't give in," Kate responded softly. "But anything either one of you could tell us about what his special skills entailed, could be helpful in tracking down his killer."

"I never understood it," Fariq, confided. "It had to do with how things spread, how things scatter. I believe Amir originally intended to apply it to agriculture."

"Yes," he said he worked with patterns," Nazihah added. "He actually found that helpful as a cab driver, figuring out how traffic would flow. He said it made his trips faster, so he could pick up more fares."

Kate thanked Nazihah and Fariq. Both she and Castle re-offered their sympathies and returned to Kate's unit. Castle scrubbed a hand over his face as he sat beside Kate. "Scatter patterns. Kate, that's just what someone would need to understand how to build the most efficient dirty bomb. The more they could spread the radioactivity around, the more havoc they could wreak and the more difficult the cleanup."

Kate turned the key harder than necessary to start the car. "I know, Castle. We're just going to have to figure out who would have known enough to try to get that information out of Amir and who could have put their hands on enough cesium to build a bomb. The intersection of those two paths should give us both Amir's murderer and our potential bomb builder."

Captain Montgomery called a strategy meeting in the conference room and introduced the representative from Homeland Security. Agent Mark Fallon stood ramrod straight. His hair was cropped in a flat crew, with only the gray at his temples an indication of age. His eyes were dark and hard. He glared at Castle and turned to Montgomery. "What is he doing here? This situation is need to know. That means no civilians."

"I'm afraid it's a little late for that, Agent Fallon," Castle threw back. "I already know and I'm here to help."

"Castle is an out of the box thinker," Montgomery explained. "He has been able to make connections no one else saw on some of our toughest cases. You do want him here."

Fallon snorted. "That remains to be seen. Mr Castle, I'm watching you. If you leak one word of what's going on here, I'll have you arrested. Do you read me?"

"Loud and clear," Castle responded.

"Perhaps we should begin with a rundown of what we know so far," Montgomery suggested. "Detective Beckett?"

Kate gave a summary of what had been gleaned from the crime scene and what she and Castle had learned from Nazihah and Fariq. "The way I see it," she asserted, "we have two avenues of investigation and both are going to require a lot of eyes. First, we need to track down every possible source of cesium 137, find out if there were any shortages. If any has come up missing, we dig into anyone who had any possible access. That would be our connection to our killer and potential bomber.

"The other avenue is identifying the man who was seen running away from the scene of Amir's murder. CSI is snowed under, tracing all the prints found in Amir's cab. But it's possible something might pop. Almost the same thing with DNA. There was so much, it is almost impossible to identify, but they'll be looking for phenotypes that fit what little description we have. We have a dark haired Caucasian male.

"The description also implied a possible military connection. So we will be looking at members of the military that would have had an opportunity at some point to learn about Amir. Because of his military experience, I would suggest having Detective Esposito spearhead that portion of the investigation, with as many extra hands to sift through military records as he needs."

"Good call," Montgomery remarked. "And I'll put you in charge of tracking cesium 137 supplies. Let's get to it!"

"Oh my God!" Castle exclaimed, staring in horror at the monitor on the computer at the desk he'd been assigned near Kate's.

Kate turned to him. "What's wrong, Castle?"

"Cesium 137, it's everywhere! It went into the ocean from the reactor accident in Japan. It's in the drinking water of fifteen U.S. cities and it's been found in milk. I'm going to have to put a radiation detector on my refrigerator."

"Castle, that's very disturbing," Kate agreed, "but have you found anything relevant to the case?"

"Maybe," Castle mused. "Kate we might be going at this from the wrong angle. We're looking for thefts or possible large purchases. I checked, you can make small purchases of cesium 137 in several forms. It's legal for the general public to own it and doesn't even require a license. The damn stuff is drop shipped. Hobbyists can buy it, sometimes in disk form. Suppose, you either had one person buying a lot of small quantities over time or better still, a network of persons each buying a small quantity. There'd be no red flags. Then the builder decides to combine it all in a bomb, but he needs someone like Amir to figure out the best way to employ what the cesium he has to do the most damage."

"So by your theory, we would go to legitimate suppliers and look either at customers who've made a string of small purchases or a large number of small purchases made by different buyers over a short span of time?" Kate clarified

Castle nodded vigorously. "Exactly. And Kate, if I'm right, and whoever is doing this couldn't get what they needed from Amir, they'll have to go after someone else with that kind of expertise. We need to start looking for people who might fit that bill."

"Castle, how do we do that? There must be hundreds or even thousands of engineers, scientists, and mathematicians in the Greater New York area. We can't go through all of them."

"No, but we can go through papers on scatter patterns. There can't be that many of those. We look at the authors," Castle proposed, "and see who might be a likely replacement for Amir."

"Alright Castle," Kate agreed, "you look into that and I'll get started getting customer lists for small quantities of cesium 137. We'll see what we come up with, and hope we do it fast enough.