While we waited, we perused an exhibit called Jewels of the Sea, browsing Atlantic thorny oysters and Pacific lions' paws while the skull of a duckbill dinosaur watched us from a wall. There were eels and fish and crabs in jars, and tree snails and a mosasaur marine lizard found in a Kansas chalk bed. Marino was beginning to get bored when the bright brass elevator doors opened and Dr Alex Vessey stepped out. He had changed little since I had seen him last, still slight of build, with white hair and prepossessed eyes that, like those of so many geniuses, were perpetually focused somewhere else. His face was tan and perhaps more lined, and he still wore the same thick black-framed glasses.

'You're looking robust,' I said to him as we shook hands.

'I just got back from vacation. Charleston. I trust you've been there?' he said as the three of us boarded the elevator.

'Yes,' I replied. 'I know the chief there very well. You remember Captain Marino?'

'Of course.'

We rose three levels above the eight-ton African bush elephant in the rotunda, the voices of children floating up like wisps of smoke. The museum was, in truth, little more than a huge granite warehouse. Some thirty thousand human skeletons were stored in green wooden drawers stacked from floor to ceiling. It was a rare collection used to study people of the past, specifically Native Americans who of late had been determined to get their ancestors' bones back. Laws had been passed, and Vessey had been through hell on the Hill, his life's work halfway out the door and headed back to the not-so-wild west.

'We've got a repatriation staff that collects data to supply to this group and that,' he was saying as we accompanied him along a crowded, dim corridor. 'Respective tribes have to be informed as to what we've got, and it's really up to them to determine what's done. In another couple years, our American Indian material may be back in the earth again, only to be dug up again by archaeologists in the next century, my guess is.'

He talked on as he walked.

'Every group is so angry these days they don't realize how much they're hurting themselves. If we don't learn from the dead, who do we learn from?'

'Alex, you're singing to the choir,' I said.

'Yeah, well, if it was my great-grandfather in one of these drawers,' Marino retorted, 'I'm not so sure I'd feel too good about that.'

'But the point is we don't know who is in these drawers, and neither do any of the people who are upset,' said Vessey. 'What we do know is that these specimens have helped us know a lot more about the diseases of the American Indian population, which is clearly a benefit to those now feeling threatened. Oh well, don't get me started.'

Where Vessey worked was a series of small laboratory rooms that were a jumble of black counter space and sinks, and thousands of books and boxes of slides, and professional journals. Displayed here and there were the usual shrunken heads and shattered skulls and various animal bones mistaken as human. On a corkboard were large, painful photographs of the aftermath of Waco, where Vessey had spent weeks recovering and identifying the decomposing burned remains of Branch Davidians.

'Let's see what you've got for me,' Vessey said.

I set my package on a counter and he slit the tape with a pocket knife. Styrofoam rattled as I dug out the cranium, then the very fragile lower portion of the skull that included the bones of the face. I set these on a clean blue cloth and he turned on lamps and fetched a lens.

'Right here,' I directed him to the fine cut on bone. 'It corresponds with hemorrhage in the temporal area. But around it, the flesh was too burned for me to tell anything about what sort of injury we were dealing with. I didn't have a clue until I found this on the bone.'

'A very straight incision,' he said as he slowly turned the skull to look at it from different angles. 'And we're certain this wasn't perhaps accidentally done during autopsy, when, for example, the scalp was reflected back to remove the skull cap?'

'We're certain,' I said. 'And as you can see by putting the two together' - I fit the cranium back in place - 'the cut is about an inch and a half below where the skull was opened during autopsy. And it's an angle that would make no sense if one were reflecting back the scalp. See?'

My index finger was suddenly huge as I looked through the lens and pointed.

'This incision is vertical versus horizontal,' I made my case.

'You're right,' he said, and his face was vibrant with interest. 'As an artifact of autopsy, that would make no sense at all, unless your morgue assistant was drunk.'

'Could it be maybe some kind of defense injury?' Marino suggested. 'You know, if someone was coming at her with a knife. They struggle and her face gets cut?'

'Certainly that's possible,' Vessey said as he continued to process every millimeter of bone. 'But I find it curious that this incision is so fine and exact. And it appears to be the same depth from one end to the other, which would be unusual if one is swinging a knife at someone. Generally, the cut to bone would be deeper where the blade struck first, and then more shallow as the blade traveled down.'

He demonstrated, an imaginary knife cutting straight down through air.

'We also have to remember that a lot depends on the assailant's position in relation to the victim when she was cut,' I commented. 'Was the victim standing or lying down? Was the assailant in front or behind or to one side of her or on top of her?'

'Very true,' said Vessey.

He went to a dark oak cabinet with glass doors and lifted an old brown skull from a shelf. He carried it over to us and handed it to me, pointing to an obvious coarse cut in the left parietal and occipital area, or on the left side, high above the ear.

'You asked about scalpings,' he said to me. 'An eight- or nine-year-old, scalped, then burned. Can't tell the gender, but I know the poor kid had a foot infection. So he or she couldn't run. Cuts and nicks like this are fairly typical in scalpings.'

I held the skull and for a moment imagined what Vessey had just said. I envisioned a cowering crippled child, and blood running to the earth as his screaming people were massacred and the camp went up in flames.

'Shit,' Marino muttered angrily. 'How do you do something like that to a kid?'

'How do you do something like that at all?' I said. Then to Vessey, I added, 'The cut on this' - I pointed at the skull I had brought in - 'would be unusual for a scalping.'

Vessey took a deep breath and slowly blew out.

'You know, Kay,' he said, 'it's never exact. It's whatever happened at the time. There were many ways that Indians scalped the enemy. Usually, the skin was incised in a circle over the skull down to the galea and periosteum so it could be easily removed from the cranial vault. Some scalpings were simple, others involved ears, eyes, the face, the neck. In some instances multiple scalps were taken from the same victim, or maybe just the scalplock, or small area of the crown of the head, was removed. Finally, and this is what you usually see in old westerns, the victim was violently grabbed by his hair, the skin sliced away with a knife or saber.'

'Trophies,' Marino said.

'That and the ultimate macho symbol of skill and bravery,' said Vessey. 'Of course, there were cultural, religious, and even medicinal motives, as well. In your case,' he added to me, 'we know she wasn't successfully scalped because she still had her hair, and I can tell you the injury to bone strikes me as having been inflicted carefully with a very sharp instrument. A very sharp knife. Maybe a razor blade or box cutter, or even something like a scalpel. It was inflicted while the victim was alive and it was not the cause of death.'

'No, her neck injury is what killed her,' I agreed.