"No doubt," Jack said. "But it is a very, very long shot, as I explained. Yet if Patience did not have a heart attack, it opens up the possibility of many more potential agents. The other reason I came out here tonight was to look at the box of bedside biomarker assay devices in your doctor's bag. Is there any reason you can think of that your result could have been a false positive?"

Craig raised his eyebrows for a moment while he mulled the question. "I can't think of any," he said at length. "I wish I could, but I can't."

"The lab supervisor at the hospital asked me if the one you used tested for both troponin I and myoglobin or just troponin I."

"It's the one with the myoglobin. I chose to stock that one for the reason the lab supervisor mentioned – namely, it gives a result in as little as two hours."

"Is there a shelf life for those devices?"

"Not that I know of."

"Then I guess we'll just have to limit the possible agents to those capable of causing a heart attack."

"What about digitalis?" Craig suggested.

"I thought of digitalis, for sure, and it was part of the screen. So digitalis was not involved."

"I wish I could help more," Craig said. "One of the worst parts of being sued is you feel so helpless."

"You could help if you could think of any cardiotoxic drugs Patience or Jordan might have had access to."

"She had quite a pharmacopoeia in her medicine cabinet, thanks to my absent partner, Ethan Cohen. But all those records were turned over in discovery."

"I've been through those," Jack said. He got to his feet. Relaxing for a few minutes seemed to make his legs feel heavy and sluggish. It was obvious he was going to need some coffee before the night was over. "I better get back and see if the toxicologist has had any luck, and you better get back to bed." He started for the door.

"Are you going to work all night?" Craig asked, accompanying Jack.

"It looks like that," Jack said. "After everything that's happened, I wish I could be certain of some positive result, but it's not looking likely."

"I don't know what to say other than thanks for all your effort."

"You're welcome," Jack said. "And it's been positive despite the problems I've caused and the whacks I've taken. It has been nice to hook back up with Alexis."

They reached the front door. Craig pointed down toward the study. "Should I run and grab my doctor's bag so you can look at the biomarker assay box? I'm sure it's the same box. After this fiasco, I'm not making many house calls."

Jack shook his head. "I'm good. You told me what I needed to know."

"Will we see you in court tomorrow?"

"I don't think so. I've got some pressing personal plans that are dictating I take the first shuttle back to the Big Apple. So let me say, good luck!"

Jack and Craig shook hands, having become, if not friends, a bit more knowledgeable and appreciative of each other.

THE RIDE BACK into the city a little after four a.m. was a mirror of the ride out. There was traffic on the Mass Pike but very little once in the city along Mass Ave. It took Jack less than twenty minutes to get all the way to the medical examiner's office. He parked right on the side of the building in a reserved space, but since he would be leaving at such an early hour, he didn't think it would matter.

Security recognized him and let him in. As he climbed the stairs, he looked at his watch. It was coming down to the wire. In less than two hours he'd be on the plane, taxiing away from the terminal.

Walking into the library, Jack did a double take. The place was in considerably greater disarray than when he had left. Latasha looked as if she were cramming to take her medical specialty boards. There were numerous large books that she'd gathered from around the office lying open on the tabletop. Jack recognized most. They included standard internal-medicine textbooks, physiology books, toxicology books, and pharmacology books. The case file material that Jack had organized was now randomly spread out, at least according to his eye.

"What the hell?" Jack questioned with a laugh.

Latasha's head popped up from an open textbook. "Welcome back, stranger!"

Jack flipped the covers back on a couple of the books he didn't recognize. After he saw the titles, he reopened the books to where Latasha had them. He took a seat opposite her.

"What happened to your shoulder?"

Jack was continuing to press the Ziploc bag against his bruise. By now the bag contained mostly water, but it was still cool enough to be of some benefit. He told her what had happened, and she was appropriately sympathetic for him and inappropriately critical of Craig.

"It wasn't his fault," Jack insisted. "I've been so consumed by this case for a variety of reasons that I never stopped to think of what a harebrained idea it was for me to go sneaking into his house. I mean, this is after someone else had broken into it and terrorized his kids to give him a message that they'd be back if I did an autopsy. And I just did the autopsy, for chrissake. What was I thinking?"

"But you were a houseguest. You'd think he'd make sure who he was hitting with a baseball bat."

"I wasn't a houseguest any longer. But let's drop it. Thank God no one got hurt any more than a shoulder contusion. At least I think it is just a contusion. I might have to get my clavicle x-rayed."

"Look on the positive side," Latasha said. "You certainly made sure he wasn't comatose, you know what I'm saying?"

Jack had to smile in spite of himself.

"What about the biomarker assay kit? Did you find out anything?"

"Nothing that raised the possibility he'd gotten a false positive. I think we have to assume it was a legitimate result."

"I suppose that's good," Latasha said. "It eliminates a lot of potential lethal agents." Her eyes swept over the books she had arranged around her.

"It looks like you've been busy."

"You have no idea. I got my second wind with the help of a few Diet Cokes. It's been like a great review course in toxicology. I haven't studied this stuff since forensic boards."

"What about Allan? Has he called you?"

"Several times, to be exact. But it's good. The more I hear his voice, the easier it is not to drag up old memories and get pissed."

"Has he had any luck?"

"Nope. Not at all. Apparently, he's trying to impress me, and you know something? He's not doing such a bad job. I mean, I knew he was smart and all back in college with his majoring in chem, math, and physics, but I didn't know he'd gone on to get a Ph.D. at MIT. I know that takes a few more brains than medical school, where perseverance is the major requirement."

"Did he say what kinds of things he's ruled out?"

"Most of the more common cardiotoxic agents that were not on the screen. He also explained to me some of the tricks he's using. The embalming chemicals are making it much harder with the tissue samples, like from the heart and liver, so he's concentrating on the fluids, where there's been less contamination."

"So what's with all these textbooks?"

"I started by reviewing cardiotoxic agents, a lot of which, I learned, could cause heart attacks or at least enough damage to the cardiac muscle so that clinically it would present as one even though there was no occlusion of cardiac vessels. I mean, that's what we've found from the autopsy. It's also what I found on the frozen sections we stained. I took a peek at a couple of the slides while you were gone. The capillaries look normal. I left the slide in the microscope in my office, if you'd like to take a peek."

"I'll take your word for it," Jack said. "I didn't expect we'd see anything as clear as the gross was."

"Now I've expanded from purely cardiotoxic agents to neurotoxic agents, since a lot of them do both. I tell you, it's fascinating stuff, especially how it dovetails with bioterrorism."