That, of course, was not the sort of question you generally wanted to ask Marcus or Lucius, unless you were in the mood for a very long lecture on some budding branch of forensic science. In this particular case, Mr. Moore and I were treated to forty-five uninterrupted minutes on the new field of ballistics, a clinic made all the more complete by Miss Howard’s participation. Put simply, ballistics seemed to amount to the firearms equivalent of fingerprinting: earlier in the century, an Englishman had discovered that bullets, when they passed through the barrel of a gun, were marked by whatever distinctive defects (nicks in the metal and the like) characterized said barrel. By 1897, when almost all pistols and long arms had rifled barrels, it’d been found that bullets were also marked by the rifling itself, which was made up of what were called “grooves and lands.” The grooves were the spiral tracks what were carved on the inside of the barrel (rotating toward either the right or the left) to make the bullet spin as it came out of the muzzle and thereby fly much straighter through the air; the lands were the spaces between these grooves. Bullets propelled through said grooves and lands were marked by lines that exactly reflected the specific rifling of the particular barrel. This system of identification had already claimed some success, though not in the United States: some years earlier, a French colleague of the detective sergeants’, one Monsieur Lacassagne, had matched the number, spacing, and twist of grooves on a bullet taken from a dead man to the barrel of a gun owned by a suspect. The man was afterward convicted, mostly on the strength of the ballistic evidence.

Now, this judgment had, the detective sergeants admitted, been a little premature, seeing as the lands and grooves of guns had never been catalogued even by manufacturer or model, much less by the individual characteristics of specific pieces; so it was possible that somebody else in France had owned a weapon with the same arrangement of lands and grooves as the gun what belonged to the fellow who’d been convicted. But the fact remained that there were now three ways to try to determine if a given bullet had come from a particular firearm: first, obviously, there was the caliber size; then there were particular marks left by defects in the barrel (not that every gun necessarily had such defects, but many did); and finally, there were the number and twists of the lands and grooves. Convincing as all this might’ve seemed, though, even a match between a bullet and a gun on all three counts couldn’t yet be considered the last word on identification, being as, again, there was no central authority that required gun manufacturers to register the individual specifications of each of their models: the possibility still existed that a given bullet what matched a given gun according to caliber, defects, and grooves and lands had actually been fired by some unknown matching weapon. Oh, sure, ballistic experts like the detective sergeants could protest that the chances of any two guns having exactly the same specifications were somewhere in the neighborhood of a million to one; but even a million to one left room for doubt, and so, while ballistic evidence had become what you might call mighty handy to modern-thinking investigators, it still wasn’t accepted as legally conclusive.

By the time the Isaacsons and Miss Howard had finished explaining this bit of business to Mr. Moore and me, I’d pretty well finished the job of getting my bit of metal free of the board; but my spirits, which had started to race at the prospect of actually being able to put a bullet to the ballistics test, sank considerably when I realized that I’d spent the better part of an hour carefully preserving an old nail head. Such discouragement, though, was common to detective work, I knew that much: so I picked up my magnifying lens and continued going over the surface of the wood, looking for another likely hole. Lucius, Marcus, and Miss Howard, meanwhile, continued their lecture, explaining what the younger Isaacson brother was up to with Daniel Hatch’s Colt: for ballistics didn’t begin and end, it seemed, with the matching of bullets to barrels. Lucius also had to carefully try to determine, based on the amount of rust and powder buildup on the Peacemaker, how recently it’d been fired, and how many times. The second question seemed easy enough to answer: there were three cartridges still in the six-shooter, giving the impression that three shots had been fired. This came as no big surprise: three was the number of bullets we’d expected to be involved in the shooting of Libby Hatch’s children. But, as usual when you were dealing with forensic science, things weren’t as simple as they appeared.

It was general practice, Miss Howard explained, for people who kept pistols in their homes to leave one chamber empty at the top position, so that if something or someone accidentally happened to catch the hammer without cocking it, the firing pin wouldn’t slam back down on anything but air. And as Lucius’s examination went on, the three of them became ever more convinced that Daniel Hatch had followed this procedure. Three chambers of his gun were, like I say, still loaded; but of the remaining three, only two had the kind of powder deposits that would indicate they’d been fired since the gun’s last cleaning. On top of that, the third empty chamber had a larger buildup of rust than the other two, indicating it’d been vacant longer. And as for the unlikely chance that somebody had found the gun, shot it, reloaded it, and dumped it back down the well, Marcus and Lucius felt they could rule that out by the measurement they took of the amount of rust in the barrel: the gun hadn’t been fired in years.

This was all very disturbing. For our theory that Libby Hatch had herself shot her three children to work out, we appeared to need three shots to’ve been fired; but only two had been discharged from the Colt. This gap perplexed Marcus and Lucius mightily, and as they continued to dust the gun for fingerprints, their faces grew as knotted as the old trees out in the yard. They did find several prints that matched Libby’s on both the gun’s grips and its trigger; and there was a partial print on the hammer what they felt comfortable labeling as hers, too; but there was no sign that she’d ever touched the cylinder, which appeared to rule out the possibility that she’d reloaded and refired the thing at any point. We knew that one bullet had traveled clear through Clara Hatch s neck (and hopefully lodged in some part of the wagon, probably the underside of the driver’s bench); but if only one other shot had been fired, how could we account for two dead boys?

Their mood getting nothing but more glum, Marcus and Lucius carefully recorded all their opening findings on the condition of the gun, and then began to disassemble the thing to get it ready for the test firing. It was Miss Howard who brought hope back into the picture by coming up with a possible solution to the riddle of two bullets and three victims. Going for the stack of Mr. Picton’s files on the shooting, which were lying inside on the piano, she pulled out Dr. Lawrence’s postmortem report on the two Hatch boys, reminding us that nowhere in the thing was there any reference to exit wounds on either Thomas’s or Matthew’s body. And while Lawrence did say that there were powder burns on the children, he didn’t specifically state which children: Mr. Picton had assumed he’d meant all three, being as they’d all suffered gunshot wounds. But that might not’ve been the case. As for Libby Hatch’s statements about what positions the kids’d been in when they were shot, we couldn’t accept those any more than we could believe anything else the woman had said. So we were free, inside of certain limits, to imagine an entirely different sequence of events from the one that Mr. Picton had dreamed up on the basis of the reports.