By the lime the paramedics came, Nick had retreated to the street. It was paved in front of Torres's house, and someone had scraped his tires against the curb and left rubber in the street as he peeled out. After setting rulers next to the tread marks for scale, Nick photographed them. He had shot some pictures of the porch, too, but mostly just so he would remember the layout. The photos would have no standing in court at all, after everybody had moved around so much. Then he flaked some rubber bits off the curb into a plastic evidence bag, in case he had occasion later to match it to actual tires.

In his experience, most people underestimated how truly unique a tire mark was. They thought if someone took an impression of their tires from a crime scene, all a suspect would have to do was point out how many similar tires were purchased in any given year. But Nick could point to all of the different variables in a tire track, the grooves and ribs, the sipes and lugs and slots, and show how an individual tire print was almost as good as a fingerprint at singling out a specific vehicle. He actually enjoyed being in court on those occasions, watching the faces of suspects when their certainty of exoneration turned into terror of certain conviction.

As long as he was out in the road, he also took pictures of brass shell casings, ejected from the automatic weapons as they were fired out the window. One of the shooters had used 9 mm ammo, standard fare for urban thugs, but the other had been firing.50-caliber cartridges. That made Nick nervous, because that shooter was armed for war. He collected the casings, bagging each one individually and labeling each bag, just as he would if the evidence was intended for his own crime lab. The shell casings would have rifling marks that could be compared with any weapons recovered later, and they might carry fingerprints.

When he had gathered all of the evidence he could get in the street, he turned his attention back to the porch. The paramedics had taken away all of the gunshot victims, and there were only a couple of tribal cops left behind. They paid little attention to Nick, interacting with him only occasionally and for the most part letting him do his work.

Something about the shooting of Meoqui Torres bothered him, but he couldn't put his finger on what it was. When he had arrived with Brass and Aguirre, Torres had been lying on the floorboards, and it had seemed cut and dried. But he had learned not to disregard his instincts in cases like this. He stood on the porch again, eyeing the scene, re-creating in his mind what he believed had happened.

Torres had been leaning against the wall, shooting the breeze with his buddies, talking about Domingo's death, most likely, and how it would affect the tribe. Maybe Torres had even been sitting on the porch – not in one of the chairs but on the floor, back against the wall or cross-legged – and he stood up when that pickup truck came to a stop at the curb. Perhaps he recognized the truck, knew that the men in it weren't friendly. Either way, when the shooting started, that's where he was, standing there just beside the window. One of the first rounds struck him in the thigh. That had been one of those big.50-caliber rounds. Reeling from that shot, Torres had turned away from the street, and the next bullet, one of the nine-mils, caught him in the shoulder. He had fallen then, hitting his head against the corner of the windowsill.

Nick realized what wasn't sitting right with him.

He had found Torres on the ground a foot or so from that window. The wall behind the porch was pockmarked with bullet holes, but he couldn't see any that corresponded directly to Torres's shoulder wound. The window was open, and more rounds had gone inside, but Torres had been too close to the wall and too far from the window for the shot that hit his shoulder to have flown through that.

So where had it gone? The shot was definitely a through-and-through, leaving a good-sized exit wound on its way out.

Besides, if Torres had spun around so that he faced the house, he should have struck the window-sill with the front of his head, not the back. He might have continued spinning, the trapezius shot even increasing his momentum. But Nick was beginning to think it hadn't gone down that way after all.

He went back to the Yukon and took out a dummy and some trajectory rods with built-in laser pointers. These would help him better visualize Torres's position and locate the bullet.

Getting the dummy placed where he believed Torres had been standing at first, he inserted one of the rods into Torres's thigh. He wished he'd been able to get pictures of Torres's wounds before those guys had spirited him away, but he thought he remembered the positions well enough at least to get close to the mark.

With the dummy and rod in place, he checked the laser beam. It shone straight into the street. Just to make sure. Nick walked over there, waving his hand in front of the beam to check its location. When he reached the street, he looked at where the beam landed in comparison with where the tire marks he'd found against the curb were. Based on that, he adjusted the dummy slightly and repeated the process. The laser ran straight through where the pickup's passenger window would likely have been. No one had mentioned the truck being jacked up, so Nick had to operate on the belief that it was a standard truck.

That part done, he tried to reenact Torres's motions using his own body, then to duplicate what he came up with using the dummy. He imagined the brute force of that big slug's impact, the heat of entry, the shock that Torres must have felt as his thigh muscles were torn away. He would have fallen backward, spinning around -

"Hey, you okay?" One of the tribal cops stood in the yard, a young woman with her hair in a long ponytail, watching him. Nick must have looked as if he was having some kind of seizure.

"Yeah, I'm fine. Just trying to re-create one of the shootings."

"Is that what the lasers are for? That's pretty cool."

"That's right," Nick said. "They're for determining trajectory, showing where someone shot from."

"That's awesome." She turned away, as if she was afraid that she had intruded on some personal moment, and walked back to where a clutch of other cops stood together at the edge of the yard.

Nick went back to what he was doing, trying to work out how Torres had spun. But no. That's where the theory fell apart. Now that he acted it out and tried to make the dummy go through the motions, he knew that Torres would not have spun away from the first shot. His damaged leg wouldn't have supported that sort of movement. He would have fallen back, past the window, bounced off the wall, and dropped to the floor.

No matter how Nick tried to make it happen, that second shot, through the trapezius, had not come from the truck. It couldn't have.

Which left only one option: the window.

The people on the porch and inside the house had returned fire, they said. Nick had seen plenty of spent rounds out in the street and beyond to back up that story. He didn't think it would be possible to isolate which one had hit Torres, at least not without a lot of lab time testing each one for his DNA. But when he put the dummy through the paces he had laid out for it, the trajectory rods confirmed his theory. The shoulder shot had to have been fired from inside, behind Torres, and at pretty close range. Torres started to fall forward, hit the porch's front rail, and bounced off that. His legs gave way, and he fell back, striking his head on the windowsill and then slumping to the floor.

Which meant the second shot was an accident, someone pulling the trigger as Torres fell into his line of fire…

Or else someone had intentionally shot the activist from inside the house. Someone he had probably trusted.