Owen glanced dubiously at the air-conditioning vents overhead. “You probably want to take a look at the mold spores, too.”

“Your Honor, I have allergies,” George said. “Yet I’ve been perfectly comfortable in this courtroom.”

Owen looked aggrieved. “I can’t help my high level of sensitivity.”

“Dr. Zeigler, do you feel that you’ll be able to make it through your testimony? Shall I see about procuring another courtroom?”

“Or maybe a plastic bubble,” George muttered.

Owen sneezed again. “I’ll do my best.”

The judge kneaded her temples. “You may continue, Ms. Hathaway.”

“Dr. Zeigler,” I said, “did you examine the tissue samples from Baby Fisher?”

“Yes. The infant was a premature liveborn male with no congenital abnormalities. There was evidence of acute chorioamnionitis and infection in the baby. The cause of death was perinatal asphyxia.”

“Your findings, then, did not disagree with those of the medical examiner?”

Owen smiled. “We agree on the cause of death. However, regarding the proximate causes of death-the events leading up to the asphyxia-our analyses are markedly different.”

“How so?”

“The medical examiner found the manner of death to be homicide. I believe the infant’s asphyxia was due to natural causes.”

I let the jury absorb that for a moment. “Natural causes? What do you mean?”

“Based on my findings, Ms. Fisher did not have a hand in her newborn’s death-it stopped breathing all by itself.”

“Let’s walk through some of those findings, Doctor.”

“Well, the most puzzling was liver necrosis.”

“Can you elaborate?”

Owen nodded. “Necrosis is cell death. Pure necrosis is usually caused either by congenital heart abnormalities, which this newborn didn’t have, or by infection. When the ME saw the necrosis, he assumed it came part and parcel with the asphyxia, but the liver has a dual blood supply and is less susceptible to ischemia than other organs.”

“Ischemia?”

“Tissue hypoxia-lack of oxygen-caused by this loss of oxygen in the blood. Anyway, it’s very unusual to find this sort of lesion in the liver. Add this to the chorioamnionitis, and I started to wonder if an infectious agent might have been at work here, after all.”

“Why would the medical examiner have overlooked this?”

“A couple of reasons,” Owen explained. “First, the liver showed no signs of polys-white blood cells that respond to a bacterial infection. However, if the infection was very early, there wouldn’t have been a poly response yet. The ME assumed there was no infection because there was no inflammatory response. But cell death can occur several hours before the body responds to it by mounting an inflammation-and I believe the infant died before this could happen. Second, his cultures showed no organism that would have been a likely cause of infection.”

“What did you do?”

“I got the paraffin blocks of tissue and did Gram’s stains on the liver. That’s when I found a large number of cocco-bacillary bacteria in the neonate. The ME chalked these up to contaminants-diphtheroids, which are rod-shaped bacteria. Now, cocco-bacilli are often misidentified as either rod-shaped bacteria, like diphtheroids; or cocci, like staph or strep. There were so many of these organisms I began to wonder if they were something other than mere contaminants-like perhaps an infectious agent. With the help of a microbiologist, I identified the organism as Listeria monocytogenes, a motile pleomorphic Gram-positive rod.”

I could see the eyes of the jury glazing, bogged down in scientific terms. “You can say that again,” I joked.

Owen smiled. “Let’s just call it listeriosis. That’s the infection caused by these bacteria.”

“Can you tell us about listeriosis?”

“It’s an often unrecognized cause of preterm delivery and perinatal death,” Owen said. “Infection in the second or third trimester usually leads to either stillbirth or preterm birth followed by pneumonia and neonatal sepsis.”

“Hang on a second,” I said. “You’re saying that Katie contracted some infection that may have compromised the health of her baby before it was even born?”

“That’s exactly what I’m saying. Moreover, it’s extremely difficult to diagnose in time to initiate therapy. The mother will exhibit flu-like symptoms-fever, aches, mild pain-only hours before the premature delivery takes place.”

“What is the effect on the newborn?”

“Perinatal depression, fever, and respiratory distress.” He paused. “The mortality rate for the newborns, in case studies, is somewhere between thirty and fifty percent even after treatment.”

“An infant infected with listeria has a fifty percent chance of dying even if treated?”

“Correct.”

“How do you contract listeriosis?” I asked.

“From the studies I’ve seen, eating contaminated food is the most frequent mode of transmission. Particularly unpasteurized milk and cheese.”

“Unpasteurized milk,” I repeated.

“Yes. And people who are in contact with animals seem to be at particular risk.”

I put my hand on Katie’s shoulder. “Dr. Zeigler, if I gave you the autopsy report for Katie’s newborn, and then told you that Katie lived on a dairy farm, drank unpasteurized milk daily when she was pregnant, and was actively involved in the milking of the cows twice a day, what would you infer?”

“Based on her living conditions and potential exposure to Listeria monocytogenes, I’d say that she contracted this infection when she was pregnant.”

“Did Baby Fisher exhibit the symptoms of an infant infected with listeriosis?”

“Yes. He was born prematurely and suffered respiratory failure. He showed some signs of granulomatosis infantiseptica, including liver necrosis and pneumonia.”

“Could it have been fatal?”

“Absolutely. Either from the complications of perinatal asphyxia, or simply from the infection.”

“In your opinion, what caused Baby Fisher’s death?” I asked.

“Asphyxia, due to premature delivery, because of chorioamnionitis secondary to listeriosis.” He smiled. “It’s a mouthful, but it basically means that a chain of events led to death by natural causes. The baby was dying from the moment it was born.”

“In your opinion, was Katie Fisher responsible for her baby’s death?”

“Yes, if you want to get technical about it,” Owen said. “After all, it was her body that passed on the Listeria monocytogenes to her fetus. But the infection certainly wasn’t intentional. You can’t blame Ms. Fisher any more than you’d blame a mother who unwittingly passes along the AIDS virus to her unborn child.” He looked at Katie, sitting with her head bowed. “That’s not homicide. It’s just plain sad.”

To my delight, George was clearly rattled. It was exactly what I’d been counting on, actually-no prosecutor was going to dig up listeriosis on his own, and certainly it was nothing George had thought to ask about during the deposition. He stood up, smoothing his tie, and walked toward my witness.

“Listeria,” he said. “Is this a common bacteria?”

“Actually, it’s quite common,” Owen said. “It’s all over the place.”

“Then how come we’re not all dropping like flies?”

“It’s a very common bacteria, but a fairly uncommon disease. It affects one in twenty thousand pregnant women.”

“One in twenty thousand. And it hit the defendant full force, or so you said, because of her tendency to drink unpasteurized milk.”

“That’s my assumption, yes.”

“Do you know for a fact that the defendant drank unpasteurized milk?”

“Well, I didn’t personally ask her, but she does live on a dairy farm.”

George shook his head. “That doesn’t prove anything, Dr. Zeigler. I could live on a chicken farm and be allergic to eggs. Do you know for a fact that every time the defendant reached for a pitcher at the dinner table, it contained milk-rather than orange juice, or water, or Coke?”