More key clicking and a new image appeared. The lines now plunged together from upper left to lower right, converging at a point two thirds of the distance from the bottom of the screen, then spreading slightly like stems on a bunch of dried flowers.

"The program can also produce a side view, which is necessary to estimate the height of the source of blood. By combining the two views you have a pretty accurate idea of point of convergence and, therefore, of victim position."

Gilbert leaned back and looked at me.

"So what do you want to know about the Cherokee scene?"

"Anything you can tel me."

For the next forty minutes I listened and watched, interrupting only for clarification. Gilbert was patient and thorough as he walked me through the bloodbath in the apartment.

What he said increased my conviction that Claudel was leading us in a dangerously wrong direction.

Chapter 23

The screen was fil ed with hundreds of tiny dots, like the spray-paint mist in Gilbert's test room. Scattered among them were smal bits of flesh and bone.

"You're looking at a section of the north wal , right behind the victim's chair. That's forward spatter."

"Forward spatter?"

"From the pel ets exiting Cherokee's head. Blood from an entrance wound is cal ed back spatter. Look at this."

Gilbert hit the keys and a new image fil ed the screen. It was a similar spray of aerosolized blood, though less densely packed, and lacking the larger globs of tissue.

"That's from the TV. When the pel ets struck Cherokee, blood flew backward."

"He was shot sitting in the chair?"

"Yes."

He entered several more keystrokes and the image was replaced by a view of the chair where the body had been found. Lines ran diagonal y from the wal and the TV and crossed at a point headhigh above the seat.

"But the gunshot was icing on the cake. If he wasn't dead already, he was wel on his way. Look at this."

More keystrokes. Another image, this one with larger spots and more variation in their size.

"That's medium-velocity spatter. It was al over the northwest corner of the apartment."

"But -- "

"Just wait."

He brought up another frame. This one showed spots slightly larger than those in the previous image, but of roughly uniform size. They varied in shape from round to ovoid.

When Gilbert hit a key and zoomed out I could see that most of this spatter was distributed in a long curving line, with some drops lying to either side of the arc.

"That's from the ceiling."

"The ceiling?"

"It's what we cal a cast-off pattern. It results from blood being thrown from a moving object, like my stick. When swinging a weapon, the attacker terminates his backstroke abruptly, then reverses direction to deliver the next blow. Most blood flies off on the backstroke, at least if there's enough force, but some can be thrown on the downward stroke, too."