I LEFT CLAIRE'S ROOM on the fifth floor and took the stairs to the Pediatric ICU on two. I was bracing myself for what was sure to be an awful, heart-wrenching interview.

I thought about young Tony Canello, watching his mother taking a bullet an instant before being shot himself. I had to ask this child if he'd ever seen the shooter before, if the man had said anything before or after firing the gun, if he could think of any reason why he and his mom had been targeted.

I shifted my shopping bag from my right hand to my left as I took the last flight of stairs, knowing that how I handled this interview was going to stay with this little boy forever.

The police department keeps a stash of teddy bears to give to children who've been traumatized, but those small toys seemed too cheap to give to a kid who'd just seen his mother violently killed. I'd stopped off at the Build-A-Bear Workshop before coming to the hospital and had a bear custom-made for Tony. Before it was dressed in a soccer outfit, a fabric heart had been stitched inside the bear's chest, along with my wish that Tony would get well soon.

I opened the door to the second floor and stepped into the pastel-painted corridor of the Pediatric Unit. Cheery murals of rainbows and picnics lined the walls.

I found my way to the Pediatric ICU and flashed my badge for the nurse at the desk, a woman in her forties with graying hair and large brown eyes. I told her that I had to talk to my witness and that I wouldn't take more than a couple of minutes.

"You're talking about Tony Canello? The little boy who was shot on the ferry?"

I said, "I have about three questions. I'll make it as easy on him as possible."

"Ah, I'm sorry, Lieutenant," the nurse said, holding my eyes with hers. "His surgery was touch and go. The gunshot wound involved several major organs. I'm sorry to tell you we lost him about twenty minutes ago."

I sagged against the nurses' station.

The nurse was speaking to me, asking if she could get me anything or anyone. I handed her the shopping bag with the Build-A-Bear inside and asked her to give it to the next kid who came into the ICU.

Somehow, I found my car in the lot and headed back to the Hall of Justice.

THE HALL IS A GRAY granite cube of a building that takes up a full block on Bryant Street. Its grungy and dismal ten floors house the superior court, the DA's offices, the southern division of the SFPD, and a jail taking up the top floor.

The medical examiner's office is in an adjacent building, but you can get there by way of a back door in the Hall's ground floor. I pushed open the steel-and-glass doors at the rear of the lobby, exited out the back of the building, and headed down the breezeway that led to the morgue.

I opened the door to the autopsy suite and was immediately enveloped by frosty air. I walked through the place as if I owned it, a habit encouraged by my best friend, Claire, the chief medical examiner.

But of course Claire wasn't on the ladder taking overhead shots of the deceased woman on the table. The deputy chief, a fortysomething white man, five eight or so with salt-and-pepper hair and black horn-rimmed glasses, had taken her place.

"Dr. G.," I said, barreling into the autopsy room.

"Watch where you're stepping, Lieutenant."

Dr. Humphrey Germaniuk had been in charge of the ME's office for about six hours, and already stacks of his papers lined the walls in neat rows. I used the toe of my shoe to straighten the pile that I'd accidentally dislodged, lined it up just right.

I knew Germaniuk to be a perfectionist, fast with a joke, and great on the witness stand. In fact, he was as qualified to be CME as Claire was, and some said that if Claire ever stepped down, Dr. G. would be a shoo-in for her job.

"How's it going with Andrea Canello?" I asked, nearing the body on the autopsy table. Dr. G.'s "patient" was nude, lying faceup, the gunshot wound centered between her breasts.

I leaned in for a closer look, and Dr. Germaniuk stepped between me and the dead woman's body.

"No trespassing, Lieutenant. This is a cop-free zone," he cracked – but I could see he wasn't kidding. "I've already had a suspected child abuse, a traffic fatality, and a woman whose head was opened up with a steam iron.

"The ferry victims are going to be an all-day sucker, and I'm just getting started. If you have any questions, ask me now. Otherwise, just leave your cell number on my desk. I'll call you when I'm done."

Then he turned his back on me and began to measure Andrea Canello's gunshot wound.

I stepped away, my head throbbing from the angry outburst I was keeping in check. I couldn't afford to alienate Dr. G., besides which, he was within his rights. Without Claire, the already understaffed ME's office was in a state of emergency. Germaniuk barely knew me, and he had to protect his department, his job, the rights of his patients, and the overall integrity of the investigation.

And he had to autopsy every one of the ferry victims himself.

If a second pathologist got in on this multiple homicide, a good defense attorney would pit the two pathologists against each other, look for inconsistencies that would undermine their testimonies.

Assuming we would find the psycho who killed these people.

And also assuming we would bring him to trial.

It was almost four in the afternoon. If Andrea Canello was Germaniuk's first ferry victim, his all-day sucker was going to be an all-night sucker, too.

Still, I had my own problems. Four people were dead.

The more time that passed, the more likely the ferry shooter would get away.

"Dr. G."

He turned from his diagram and scowled.

"Sorry if I came on too strong, but the shooter killed four people, and we don't know who he is or where to find him."

"Don't you mean three?" Germaniuk said. "I have only three victims."

"This woman's little boy, Tony Canello, died a half hour ago at San Francisco General," I told him. "He was nine. That's four dead, and Claire Washburn is sucking air through a chest tube."

A wave of sympathy swept the indignation from Dr. Germaniuk's face. The edge was gone from his voice when he said, "Tell me how I can help you."

DR. GERMANIUK USED A SOFT PROBE to gently explore the wound that had torn through Andrea Canello's chest. "It looks like a K-5 right through the heart. I wouldn't swear to it until the firearms examiner says so, but it looks to me like she was shot with a.38."

It's what I'd thought from the video, but I wanted to be certain. Jack Rooney's camera lens had swung away from Andrea Canello as soon as she was shot. If she'd lived for a moment, if she knew her killer, she might have called out his name.

"Could she have lived after she was shot?"

"Not a chance," Germaniuk told me. "Slug to the heart like that, she was dead before she hit the deck."

"That's some shooting," I said. "Six slugs, five direct hits. With a revolver."

"Crowded ferry boat, lots of people. Bound to hit some of them," said Dr. G. matter-of-factly.

We both looked up when the stainless steel doors to the rear of the autopsy suite banged open and a tech wheeled a gurney inside, calling out, "Dr. G., where do you want this?"

The body on the stretcher was sheeted, about fifty inches long. "This" was a child.

"Leave him," Germaniuk said to the tech. "We'll take it from here."

The doctor and I stepped over to the gurney. He pulled the sheet down.

Just looking at the dead child was enough to tear out my heart. Tony's skin was a mottled blue color, and he had a freshly stitched twelve-inch incision across his skinny little chest. I fought an impulse to put my hand on his face, touch his hair, do something to comfort a child who'd had the bad luck to be standing in a madman's line of fire.