I’ve held many of these during my career, some clinically spotless like this one, others dredged out of mass graves in Bosnia by a backhoe. The ones like this you see in dentists’ and doctors’ offices. They’re good for patient education, and they lend a certain macabre severity to a medical office.

The jaw opens easily on the springs screwed to the interior surfaces of the zygoma and mandible. Doing bite-mark comparisons can be long, painstaking work, but sometimes it’s a no-brainer. This is one of those times. The maxillary arch of the bite marks at the murder scenes is engraved upon my mind, and the one in this skull matches it tooth for tooth.

“Well?” says Kaiser.

“It’s a perfect match.”

As we zoom along the shore of Lake Pontchartrain toward the FBI field office, Kaiser speaks on the phone to someone who obviously has a great deal of power. My head is still pounding, the pain focused behind my eyes. The skull is riding up front on the passenger seat, next to our driver.

At last Kaiser hangs up and turns to me. “The chief of police is going batshit because I wouldn’t let Piazza arrest you. Now that I took you away from the scene, he’s calling my boss. It’s going to be a bureaucratic shitstorm.”

“Am I going to be arrested?”

“The field office is task force headquarters. If you’ll remain there a while without making a fuss, that’s your best bet for staying out of jail.”

“Look, my showing up at that motel was just lagniappe for the killer. It was the killer who tipped you where to find the murder weapon and the video equipment, and the same person gave you the motel and the skull. He’s trying to frame Malik. My showing up was just a bonus. If you figured out the suicide was staged, I was right there to blame for staging it. And with my experience, I’d know just how to do it.”

“It plays,” says Kaiser, “but I can think of a scenario that plays equally well.”

“Not your multiple personality fantasy.”

“No. The women in Group X know Malik is killing abusers, and also that he killed an innocent man. One of them is having a crisis of conscience. Like the woman who tried to kill herself, Margaret Lavigne.”

“Lavigne’s still in a coma?”

“Yes. I was actually thinking our caller might be your aunt.”

“Was the voice female again?”

“Yes.”

I turn toward the lake and watch the gray waves in silence. I suppose Aunt Ann could be making the calls. But for some reason I doubt it. If Ann paid Malik’s bail, what would so quickly turn her against him? Finding out that an innocent man had been murdered? Maybe. But I doubt that would sway her loyalty. “Were there bite marks on the face of the dead cop?”

“The worst yet.”

“These are personal attacks, John. And the bite marks are created antemortem, like torture. But the victims have to be immobilized before they’re bitten.”

“So?”

“The killer’s a woman. I’ve suspected it from the start. It’s probably one of the women in Group X.”

Kaiser blows out a stream of air. “That’s a possibility, but a very remote one given the crime signature. There’s no history of a woman ever committing sexual homicides like this. Not alone.”

“Five minutes ago you practically accused me of doing it!”

“You’re a special case. Your past, your forensic training. And I suggested you were assisting Malik. A male-female-team scenario.”

“Why not two women? We don’t know how many women there were in Group X.”

“Go on.”

“Once we connected Malik to those first two female patients, the killer knew we were getting close, even if we didn’t know it. So she planted the gun at Malik’s apartment and gave it to us. We kept getting closer, so she gave us Malik and the skull wrapped up in a neat package. Our girl is probably feeling pretty safe right now.”

Kaiser is looking expectantly at me. Something is tugging at the back of my mind, but I can’t quite make it out. “Did you get anything at all on Quentin Baptiste’s female relatives?”

“Hang on.” He calls Carmen Piazza. Their conversation is short and to the point. When he hangs up, he says, “Detective Baptiste had six female relatives by blood. A wife, three nieces, two daughters.”

“How old are the daughters?”

“Piazza didn’t have their ages, but one works as a teacher. The other is a day care worker. One of the nieces just graduated from the police academy.”

“She’d know how to shoot,” I think aloud. “So would the first victim’s daughter, I’ll bet. Moreland. An army brat? Daughter of a colonel?”

“We’ve been all over the Moreland daughter, because she was related to the first victim. She’s clean, Cat. But I’ll get the task force on Baptiste’s relatives right away. Stilla female killer is very long odds based on precedent.”

“There was no precedent for Aileen Wuornos either. Forget the past, John. Look at the evidence in front of you.”

A tall white sail appears on the horizon. It soothes me to follow it with my eyes. As my eyelids grow heavy, I remember the Valium I popped before going to the motel.

“How’s your head?” Kaiser asks.

“It hurts. I didn’t sleep well last night, so I took a Valium before I went to the motel.”

“You could have a concussion. Should we get you a CAT scan?”

“Just take me to the field office. I need to lie down.”

“If you lie down, I’m putting a nurse in the room with you.”

“Do whatever you want. I’m going to bed.”

I lean against the window and close my eyes, but my cell phone starts playing “Sunday, Bloody Sunday.” I reach into my pocket. It’s empty.

“I’ve got it,” says Kaiser, holding my screen where I can see it. “You know this number?”

“No, but that’s a Gulf Coast area code. It might be Ann. I left a message for her to call me.”

Kaiser thinks fast, then hands me the phone. “Whatever you do, don’t tell her Malik is dead.”

I nod and press SEND. “Hello?”

“Hey, Cat Woman!”

My heart thumps against my sternum. It’s Ann. I nod quickly to Kaiser, and he tenses on the seat.

“How you doing, baby girl?” Ann’s voice has the brittle quality I’ve learned to associate with her manic episodes. How do I play her?

“Not so good right now, actually,” I say in a tired voice.

“You sound like you need a drink.”

“I wish. I’m on the wagon.”

“Ouch. Your message said you knew something about Dr. Malik and me. What exactly do you know?”

“I know you paid his bail. The FBI knows, too.”

“That’s not against the law, is it?”

Ricochet-quick response. Definitely manic. “Dr. Malik is mixed up in some murders, Ann.”

A pause. Then a craftier voice comes through the phone. “ Mixed up is a pretty vague term, baby girl. Nathan couldn’t do the things they think he did. I know men, honey. He doesn’t have that in him.”

Ann knows men like an arsonist knows fire. “I’ve been talking to him quite a bit lately,” I tell her.

“Do you know where he is?” A hint of anxiety now.

“Yes.” I close my eyes. “He’s been arrested again.”

“Arrested?” The alarm in that one word is shocking. “Where?”

“Here in New Orleans. I think you should drive over and see him. I’d like to talk to you, too. Are you in Biloxi?”

“No.”

“Are you anywhere close?”

Another silence. “Sorry, baby girl. I don’t feel like I can tell you everything at this point. You know how that is. You’ve always kept some secrets yourself.”

“You’re right. But sometimes I wish I hadn’t. I wish all of us would have talked to each other more.”

“Oh, honeyme, too. I wish you could do a group with Nathan. He’s worked miracles for me.”

“I wanted to,” I reply, only half lying. “I just found out some things about my past that really messed me up. I’d like to ask you some questions. To see if some of the same things happened to you.”