He held up the X-ray film and pointed here and there on it. “And that’s exactly what happened here,” he said. “There is obvious stretching and tearing of the ligaments all over the place. This was a heavy diffuse blow with a broad, blunt instrument. The force was dissipated by the flexibility of the rib cage, but even so was sufficient to crack two of the bones.” “What kind of a blunt instrument?” Walker asked.
“Something long and hard and rounded, maybe five or six inches in diameter. Something exactly like a fencing rail, I would think.”
“It couldn’t have been a kick?”
Black shook his head.
“Emphatically, no,” he said. “A kick transfers a lot of energy through a tiny contact area. The welt at the toe of a boot is what? Maybe an inch and a half by a quarter inch? That’s essentially a sharp object, not a blunt object. It would be too sudden and too concentrated for the yielding effect to operate. We would see the cracked bones, for sure, but we wouldn’t see the ligament stretching at all.”
“What about a knee?”
“A knee in the ribs? That’s similar to a punch. Blunt, but an essentially circular impact site. The ligament stretching would show a completely different pattern.”
Walker drummed his fingers on his desk. He was starting to sweat. “Any way a person could have done it?” he asked.
Black shrugged. “If he were some kind of contortionist, maybe. If he could hold his whole leg completely rigid and somehow jump up and hit her in the side with it. Like it was a fence railing. I would say it was completely impossible.” Walker went quiet for a second. “What about the bruised shin?” he asked.
Black swapped the third file into his hand. Opened it and read through the description of the contusion again. Then he shook his head.
“The shape of the bruise is crucial,” he said. “Again, it’s what you’d get from the impact of a long hard rounded object. Like a fence rail again, or maybe a sewer pipe, striking against the front of the shin at an oblique angle.” “Could he have hit her with a length of pipe?” Black shrugged again.
“Theoretically, I suppose,” he said. “If he was standing almost behind her, and somehow could reach over her, and he swung a hard downward blow, and struck her almost but not quite parallel with her leg. He’d have to do it two-handed, because nobody can hold a six-inch diameter pipe one-handed. Probably he’d have to stand on a chair, and position her very carefully in front of it. It’s not very likely, is it?” “But is it possible?”
“No,” Black said. “It isn’t possible. I say that now, and I’d certainly have to say it under oath.”
Walker was quiet again.
“What about the collarbone?” he asked.
Black picked up the last report.
“These are very detailed notes,” he said. “Clearly an excellent physician.”
“But what do they tell you?”
“It’s a classic injury,” Black said. “The collarbone is like a circuit breaker. A person falls, and they try to break their fall by throwing out their hand. Their whole body weight is turned into a severe physical impact which travels upward as a shock wave through their rigid arm, through their rigid shoulder joint, and onward. Now, if it wasn’t for the collarbone, that force would travel into the neck, and probably break it, causing paralysis. Or into the brain pan, causing unconsciousness, maybe a chronic comatose state. But evolution is smart, and it chooses the least of all the evils. The collarbone snaps, thereby dissipating the force. Inconvenient and painful, to be sure, but not life-threatening. A mechanical circuit breaker, and generations of bicyclists and inline skaters and horseback riders have very good reason to be grateful for it.”
“Falling can’t be the only way,” Walker said.
“It’s the main way,” Black said. “And almost always the only way. But occasionally I’ve seen it happen other ways, too. A downward blow with a baseball bat aimed at the head might miss and break the collarbone. Falling beams in a burning building might impact against the top of the shoulder. I’ve seen that with firefighters.”