When he returned to the police station, Crane’s mind was careening out of control. He was unable to concentrate, or even to remember much, when he sat at a computer to write out a statement. He kept visualizing the little white hole in the window, and the woman’s head coming apart. A lawyer from the Police Association showed up to advise him. Technically the killing was a homicide, and it would be treated as such: detectives would investigate it, and a prosecutor would present their findings to a grand jury to determine if Crane should be indicted and tried for murder. This was deeply disturbing to Crane. The police chief assured him that he had nothing to fear from the process, but Crane was unconvinced. It did not help that his colleagues were looking at him strangely, or that conversations stopped when he walked into the break room. He saw his case sheet with “Murder” written on top.

Driving home that night he placed his fate in the hands of God. He parked in his driveway and prayed. Danielle came out, carrying their infant daughter. When the baby saw Crane she smiled. It was a relief for him. He took her smile as an answer from God and an affirmation of his humanity. But later in the evening, when he went to shave and shower, he found that he could not bring himself to look in the mirror. He was afraid of what he would see in his eyes. For days he was afraid that others—even strangers—were seeing him differently, too. A police psychologist told him that it was a common reaction among first-time killers, and he called it “the Mark of Cain.” He said it is hard, but it fades.

The grand jury took months to absolve Crane of blame. Afterward he was bitter. His relationship with the Frisco police—and particularly with the chief—never recovered from his sense that he had been abandoned for doing his job. Eventually he wrote a short book—in frank and skillful prose—meant as a guide to the aftermath of killing for other snipers in the field. He addressed the practical realities. He described the grand-jury experience in detail. He also recommended that police snipers condition their minds for the more difficult kills in ways that their departments could not—by cutting out magazine pictures of women and children, as well as of men in unusual profiles, and using them in private for target practice. He knew this seemed extreme, but he believed it was better to quit the trade entirely than to pretend that such shots will never come up. He did not quit the trade. The book was published in 2003 by a press that specialized in police matters. Two thousand copies were printed. The book was perhaps useful to a few people. It should have been a little thing.

But in the meantime, he had decided to join the Texas Army National Guard, essentially for the benefits and the fun. The National Guard would keep him close to home. He would serve in a scout platoon, but for only one weekend a month and two weeks a year—unless the unit was mobilized. Before taking the oath, Crane joked about the possibility. He said, “The way my luck goes, I’ll join up and the world will go to shit.” He joined up on September 5, 2001. Six days later came the 9/11 attacks. To me recently he said, “I’m a shit magnet—you’ll find that out.” The C.I.A. knows, but covers it up: 9/11 was Crane’s fault.

In July of 2002 his battalion was mobilized and sent to New Mexico to guard a sensitive installation. For a whole year al-Qaeda did not attack. When Crane returned to Frisco in the summer of 2003, his book had just been published, and the chief of police was furious about it. On Crane’s first day back on the job he was suspended with pay and was served with a letter charging him with contempt of court—for having divulged the secret workings of a grand jury. It was absurd. He hired a lawyer, who eventually settled the matter. Crane and Danielle sold the house in Frisco and moved with their daughter farther into the Dallas countryside, to a small town called Mabank, near another one called Gun Barrel City. It was late 2003. The United States was at war in Iraq and Afghanistan. He signed on as a full-time active-duty sergeant in the Texas Army National Guard. He was attached to a new battalion. The commander soon heard of Crane and his special history; he called him in, asked him to set up a program to train a lower level of long-range shooters known as “squad- designated marksmen,” and sent him off to an army sniper school near Little Rock, Arkansas, for the full formal deal himself. The course was tough. Crane excelled. After he graduated, his official military occupation for the first time became “sniper.” He was unusually well prepared for the job. Soon afterward, in May 2005, his unit was mobilized. In July of that year he shipped off with Alpha Company and Ross Walker to Afghanistan and to war.

IV.

In Vietnam, American forces killed at least 3.5 million people. In the process they fired untold billion of rounds of small-arms ammunition and dropped nearly seven million tons of ordnance—a weight three times heavier than that dropped on Germany during World War II. Afterward, the military had to recognize that its expenditure of ammunition had only helped the enemy cause. Various conflicts then came and went with little consequence except that, as a British sniper recently said to me, they helped weapons development along. Some of these weapons were newly precise missiles and bombs. The army’s rifle squads did not keep pace. When they went to war following 9/11, they carried essentially the same weapons that their predecessors had carried in Vietnam.