The Killing House

13

Fletcher placed the empty cup inside the sink on his way to the foyer.

Mass spectrometry, the method of identifying a substance’s chemical composition by separating its gaseous ions, had evolved considerably since its first application in the late 1950s, when it was used to analyse amino acids and peptides. The bulky equipment, which once took up an entire room of a forensics lab, had now been compartmentalized into a single, portable unit that could be carried to crime scenes and used at airports to detect and identify explosives, chemical-warfare agents and environmental toxins.

Fletcher placed the heavy plastic case on the dining-room table. He snapped free the latches and, from the padded foam lining, removed a heavy, rectangular unit, along with a small netbook computer and assorted cables.

As he set up the equipment, Karim hovered close by, peering through his bifocals like an anxious chemistry professor watching a student mixing potentially volatile chemicals.

‘Aren’t you about due for another cigarette, Ali?’

‘What happened to your concern about my health?’

‘I value my personal space more. Please, have a seat.’ Fletcher retrieved the two evidence bags from his trousers pocket — the spent cartridge and the slug he’d removed from his vest — and placed them on the table. Then he returned to the foyer and opened the closet door.

Sitting on the top shelf were several small plastic toolboxes holding various forensics supplies. It took him a moment to find what he needed.

‘This slug,’ Karim said as Fletcher entered the dining room. ‘It looks like a 9-mm round.’

‘It’s been modified.’

‘How can you tell?’

Fletcher placed the toolbox next to the MS device. ‘The cartridge,’ he said, pulling out a chair, ‘is a wildcat.’

‘I’m not well versed in ballistics, so you’ll have to explain it to me.’

‘The term refers to a cartridge that isn’t mass-produced. More specifically, a wildcat is a cartridge that has been modified in some way in order to optimize a certain performance characteristic such as efficiency or power.’

‘So it’s a home-made round?’

‘That was my initial suspicion, but the components show no evidence of shoddy craftsmanship. In fact, it’s quite the opposite.’ Fletcher opened his toolbox and continued to speak as he collected his items and placed them on the table. ‘While the slug contains a manufacturing stamp I don’t recognize, given the superior craftsmanship I’m inclined to believe the round was created by someone who specializes in custom-made ammunition.’

‘And the mass spectrometer will show you how the gunpowder was modified.’

Fletcher nodded. ‘My hope is that it will give us a unique chemical fingerprint, which will allow us to trace the owner — once we’ve identified the manufacturer.’

Hands covered in latex and the empty cartridge pinched between his fingers, Fletcher rubbed a cotton swab along the inner brass wall to collect the gunpowder residue. Karim came around the table to watch, then, thinking better of it, lit a fresh cigarette, entered the living room and began to pace across the oriental carpet. Sometimes he paused to examine a painting or charcoal drawing, standing in such a way as to keep Fletcher’s progress within his line of vision. Then he resumed his pacing.

Twenty minutes and two cigarettes later, Karim noticed that Fletcher was leaning back in his chair.

‘What is it?’

Fletcher didn’t answer. He propped an elbow on the table’s corner, resting his chin on a thumb as he rubbed his index finger across his bottom lip, staring at the computer screen.

Karim marched back into the dining room and, standing behind Fletcher, bent forward to read the results.

The mass spectrometry software had failed to identify the sample.

‘I was told these portable units have a limited library,’ Karim said. ‘I’ll have this sample tested in New York. My forensics people are at my lab right now. The mass spectrometer we have there is hooked up to a software library that can identify every — ’

‘That won’t be necessary.’

‘You know what this is?’

Fletcher nodded.

‘Human ash,’ he said.