“Analyzing blood spatters is mostly geometry-you take the two-dimensional pattern from the wall and project to three dimensions.”
Diane looked over at Frank. This was the blood of his friends that she was at the moment being so dispassionate about. He was already getting a five o’clock shadow and, though most of the time it made him look sexy, it now made him look more melancholy. “Are you all right with this?” she asked.
“I’m fine.” His voice was a little too sharp, but Diane took him at his word and continued.
The only way to do a good job is to find your objectivity and hang on to it like an anchor. That was one of the things that Santos took away from her-for a while.
“What I’ll be analyzing is the medium-impact spatter, and I have to measure the two axes-the length and width-of the drops.”
Frank turned his face to her, his dark eyes startled. “You’re kidding. All of them?”
“Not all, but a significant enough number to make sure I get reliable results.”
“I guess that will take all night and then some. Damn, how can you even see them?”
“It’d definitely be easier if she’d chosen plain white wallpaper. I’ll use a magnifying glass.”
She picked up the glass from her case and showed Frank magnified spatters of blood that had hit the wall.
“A spatter that hits the wall head-on at a perpendicular angle will be round. As the angle of impact gets smaller, the more elongated the drop becomes. See the little tail on most of these drops here?”
“If I hold my head just right and put my tongue between my left molars.”
“Now you’re getting the idea. The drop goes in the direction of the tail, like a comet. If you’ve ever spilled anything that has any viscosity at all, you’ve noticed that phenomenon. Ever have a bottle of ketchup blow up on you and spatter across the table?”
“As a matter of fact, that happened in a restaurant once. Covered me and the people at the next table. I impressed that date. But I don’t recollect observing the shape of the drops of ketchup.”
Diane watched his face as he smiled. He was trying hard. The thing she had remembered most about Frank was his smile-it made his eyes squint with a mischievous twinkle that made you think he was sharing a joke with you, and it never failed to make her smile back at him. This one was short-lived. She wished she was someplace else, doing anything else.
“If I were to draw a line along the longest axis of the drops, I’d have the two-dimensional point of convergence.”
“Which tells you what?” he asked.
Diane hesitated a moment, biting her lower lip.
“Go ahead and tell me. I’ll have to explain it to Star’s lawyer-or maybe throw it in Warrick’s face. No way you can make it any harder for me than the fact that they’re dead.”
“I know. I’m sorry. OK. When the perp strikes a blow on a victim, blood is spattered on whatever surface is near. All of those drops in that spatter are part of a set that defines that particular blow. For analysis purposes, they all belong together. When the perp swings his. . his weapon, it will have blood on it, and that blood will be cast off, making a trail across the wall, the ceiling or whatever, depending on how he swings it. The victim, if he isn’t unconscious with the first blow, will move around. When he is hit again, it will leave another set of spatters, but at a different angle, with a different point of convergence. Finding the different lines of convergence can tell me how many times the victim was struck and where the victim was located at the time of each blow.”
Frank nodded. “That makes sense. So if you know that the more elongated the drop, the more acute the angle of impact, then you can compute the angle. What is it? Something like, the sine of the angle equals the width over the length?”
“You are good at trig.”
“I was going to get a degree in math until my father asked what kind of job I could get with it. I went into accounting instead.”
“And that led to crime?”
“I was determined to make as little money as possible.”
Diane took out a calculator, a protractor, and a roll of trajectory string.
“What’s that? Fishing line? What else you got?”
Diane watched as he poked around in her blood-spatter analysis kit.
“I’ll attach this string to one end of a drop with a push pin, compute the angle, align the string to the angle, and anchor the other end of the string. After I do several drops that way, the strings will cross at the point of origin of the blood source. I’ll probably end up with several points of origin, all at different heights and distances from the wall. I should be able to do a fair job of reconstructing the scene when I’m finished.”
Diane hoisted her case up on the nightstand and opened it. “I’ll start by marking off sections of the wall and taking pictures of each section. After that, I’ll start measuring and recording.”
She took out a small laptop computer. “Kenneth Meyers says he’s going to give me a new laptop. Some top-of-the-line model he has.”
“Ken’s as much a go-getter as Mark Grayson, though not as obnoxious. He’s been trying to get me to recommend his computers to the Atlanta PD,” said Frank.
Diane shook her head as she reached down and plugged in her computer. “Are you going to do it?”
“I told him I’m not the one to ask. I have a tough time just getting pencils.”
“Hand me that flashlight,” she said.
“You find something?”
Diane took the light from his hand, wondering if the batteries still worked. “This is new carpet, you said. When was it laid?”
“George started complaining about it about a month and a half ago. About that long ago, I guess. What did you find?”
“A round imprint in the carpet between the nightstand and the bed.”
She angled the flashlight until it showed the depression. It was hard to see, barely there. In another day or so the new carpet would spring back up and it would be gone.
“Hold the light and let me take a couple of pictures.” Diane laid a small ruler next to the depression and snapped several photographs with her digital camera. She checked the images in the viewer to make sure she had gotten a clear picture.
“Did George keep a baseball bat by his bed?”
“I don’t know. I’ll ask Star. That does look as if the business end of a baseball bat stood there, doesn’t it? I wonder if Warrick found it.”
“I’m having a difficult time grasping the idea that she was so completely incompetent here.” Diane took a pair of calipers, measured the indentation, and recorded the information on her computer.
“I’m not saying she doesn’t have potential. She just doesn’t have the experience.”
“But letting McFarland in the crime scene. Even inexperienced criminalists know better.”
“I know. I got the impression Warrick knew Crystal-that they were friends or something. Hell, maybe Crystal did her hair.”
Diane used her digital camera and markers and began the process of photographing the bloodstained wall.
“While you’re in here, I’m going to search Jay’s room. I’d like to examine his computer, if Warrick didn’t take it. Maybe I’ll find some clue as to what he was doing out late that night.”
Diane had prepared a small maze of string when she realized it was getting dark outside. Subconsciously, she heard muted sounds of Frank in a far bedroom moving things around. Other than those muffled noises, she was aware of nothing but numbers. Tuning out the grimness, the gore on the walls, the smell of the room-there was nothing but the silent crunch of numbers creating lines of trajectory.
“How about a break?” Diane started at the sudden voice coming from the doorway.
“Oh, hey. I lost track of time.” She looked at her watch. “A break’s probably a good idea. I could use a couple of minutes out of this room.” She anchored the end of the string she was holding and the two of them went downstairs and out on the porch.