To Catch a Killer(74)

Victor groans.

I peer into his open briefcase. “You carry around the stuff to run DNA in your briefcase?”

“I do for certain things, like the agarose gel and buccal swabs. But the rest of this stuff I picked up at the superstore on the way home. They sell everything there.”

“So, it’s just normal stuff?”

“Pretty much.” Victor reaches into the bag and pulls out a brick-sized chunk of green foam, which he sets in the middle of the table. “Like floral foam, for example.”

“You’re going to use that?”

“It makes a perfect test tube rack.”

I peer over the edge of his shopping bag. “You found test tubes at the superstore?”

He smiles. “The buccal swabs come with their own tubes.”

“Oh. Good to know.”

He ticks a list off on his fingers. “But I will also need rubbing alcohol, tape, a sharp craft knife, some aluminum foil, and, oh yeah, baking soda and a pitcher.”

While I gather the requested items from various places in the kitchen, Victor twists open an unused swab kit. He then retrieves the glass we saw Chief Culson drink from. He hoists it to me and we nod to each other—a silent confirmation that we agree this was the chief’s glass.

Victor vigorously runs the swab along the rim of the glass, first along the inside and then the outside. When he’s finished, he drops the swab into the test tube. He lines up each of the samples by sticking them into the block of floral foam.

“Okay, these samples are in the same order of Miss Peters’s test.”

I give him a raised-eyebrow look. “There has to be more to it than that.”

“There is. I’m just going to power through. Stop me if you have questions, or you can just sit back and watch.”

I prop one leg up on the chair to rest my notebook against. “Best show in town.”

He shakes some baking soda into the pitcher and then sloshes in some distilled water from a bottle in his shopping bag.

“How much did you put in? That didn’t look very precise,” I say.

“It doesn’t have to be. I’m just making an alkaline buffering solution.” He rummages to the bottom of his shopping bag and retrieves a small testing kit for home aquariums. He scoops a bit of the buffering solution into the kit, adds a few drops of something red, and shakes it. Then he holds it up to the light and analyzes the results. “Close enough,” he mutters. He puts the lid on the pitcher and hands it to me. “Stick this in the fridge and put the alcohol in the freezer.”

Victor upends his shopping bag over the table, dumping out the rest of his purchases. It’s a bizarre assortment. A small plastic container about the size of half of a sandwich, and a smaller plastic soap dish, with a flimsy, hinged lid. Two small spools of electrical wire: one red, one black. Two packages of alligator clips, some wire strippers, six 9-volt batteries, and a bottle of meat tenderizer.

“Guess what this is?”

“Junk on sale that you couldn’t resist?”

Victor chuckles. “I like the sense of humor. It’s cute. This, my star pupil, is our electrophoresis chamber. Or it will be once we build it. Now pay attention. You don’t want to miss anything.”





36

Fifty percent of human DNA is identical to the DNA of a banana.





—VICTOR FLEMMING


Victor’s right. I don’t want to miss any of this.

“I don’t know how much you know about running gel,” he says. “So I’ll just skim the basics.”

“Pretend I don’t know anything. Tell me everything.” I scoot my chair in close.

“The test is called electrophoresis. It’s a process that uses electrical current to move particles through a fluid or, in our case, a gel.”

Victor snaps the lid off of the plastic soap dish then uses the knife to carve away each end, creating a U-shaped shell. He holds it up and rotates it. “This is the gel casting tray. The gel goes in here.” He picks up a slightly larger plastic container. “This is the buffering chamber.” He demonstrates how the smaller tray fits inside the larger one. “That alkaline solution I put in the fridge goes in here.”

I make a quick sketch of these items in my notebook and label them.

Victor rips into the packages of wire, cuts off an eight-inch piece of red and one of black, and then proceeds to strip off the coating at each end and attach the shiny copper tips to the alligator clips.

“It’s starting to look electrical.” I remember the new equipment in Miss P’s lab. There was a clear acrylic tray that had similar red and black wires attached to it.

Victor sets the wires aside and creates two strips of aluminum foil, which he folds over each end of the buffering chamber. “The aluminum foil makes the contact point on the buffering chamber,” he says.

He clips a black wire over the foil at one end of the chamber and the red wire over the foil at the other end. “Black is negative and red is positive.” He sets the contraption in the middle of the table. “That is pretty much all there is to an electrophoresis chamber.”

I turn it over and inspect it from all angles. It looks exactly like a plastic soap dish inside of a sandwich keeper, wrapped in aluminum foil and wired up. But even though it’s primitive, it closely resembles the one I saw shoved aside in Miss Peters’s lab. “Why does it need a current?” I ask.