Rich Sinclair’s work area was carpeted and well lighted, and overlooked the coliseum, which had always reminded me of a metal mushroom about to take flight. He was using weights to test the trigger pull of a Taurus pistol, and Marino and I walked in to the sound of the hammer clicking against the firing pin. I was not in a chatty mood and did my best not to seem rude as I told Sinclair outright what I needed, and that I needed it now.

“This is the metal turning from Warrenton,” I said, opening that evidence button. “And this is the one recovered from the body in the Lehigh fire.”

I opened that evidence button next.

“Both have striations that are clearly visible on SEM,” I explained.

The point was to see if the striations, or toolmarks, matched, indicating that the same instrument had been used to produce the magnesium shavings that had been recovered thus far. The ribbons of metal were very fragile and thin, and Sinclair used a narrow plastic spatula to pick them up. They weren’t very cooperative and tended to jump around as if they were trying to escape as he coaxed them from their sea of cotton. He used squares of black cardboard to center the shaving from Warrenton on one, and the shavings from Lehigh on the other. These he placed on stages of the comparison microscope.

“Oh yeah,” Sinclair said without pause. “We’ve got some good stuff.”

He manipulated the shavings with the spatula, flattening them some as he bumped the magnification up to forty.

“Maybe a blade of some type,” he said. “The striations are probably from the finishing process and end up being a defect because no finishing process is going to be perfectly smooth. I mean, the manufacturer’s going to be happy, but he’s not at our end seeing this. There, here’s an even better area, I think.”

He moved aside so we could take a look. Marino bent over the eyepieces first.

“Looks like ski tracks in snow,” was his comment. “And that’s from the blade, right? Or whatever?”

“Yes, imperfections, or toolmarks, made by whatever shaved this metal. Do you see the match, when one shaving is lined up with the other?”

Marino didn’t.

“Here, Doc, you look.” Sinclair got out of my way.

What I saw through the microscope was good enough for court, the striations of the Warrenton shaving in one field of light matching the striations of the shaving in the other. Clearly, the same tool had shaved something made of magnesium in both homicide cases. The question was what this tool might be, and because the shavings were so thin, one had to consider a sharp blade of some type. Sinclair made several Polaroid photographs for me and slid them into glyassine envelopes.