To Catch a Killer(75)

“The current mobilizes the individual DNA strands, moving them through the gel. The smaller the strand the farther it will travel.”

“But you don’t plug it in, right?” I ask.

“Nope. Six nine-volt batteries will run this baby in about forty-five minutes.” Victor unwraps the economy pack of 9-volt batteries and builds a little battery pyramid—three batteries on the bottom (tops up) and two batteries on top (tops down) all plugged in to one another. This arrangement leaves one terminal open on each end. “In the field test you can’t always rely on having available power,” he explains. “So, you need an alternative.”

I sketch his battery arrangement in my notebook. “I didn’t know you could plug one battery into another.”

“It’s called connecting them in series.” Victor touches the alligator clips. “I won’t do it now, but all I have to do is clip the red side to the positive terminal on your stack of batteries and the black side to the negative terminal and voilà, electrical current.”

I check the time on my phone. It’s still early; Rachel and the chief are probably just arriving at the opera. We have plenty of time.

“Now we make the agarose gel.” Victor is standing near the microwave and mimes a slight mad-scientist expression as he tears open a small envelope of powder he retrieved from his briefcase. He taps the contents into a glass measuring cup that already contained distilled water. He stirs the two ingredients together for a minute then holds up the cup for my inspection.

“It’s cloudy,” I say, wrinkling my nose.

He pops the measuring cup into the microwave and heats it for a few seconds.

“We actually have to melt it to be sure all the particles are removed,” Victor says.

While the cup containing the gel is heating, I notice Victor applying tape to the open ends of the soap dish. “Wait. You just cut that off. Was that a mistake?”

“Hey. You’re paying atttention,” Victor says. “I like that.” He holds the plastic tray up, gesturing to how it is formed. “Remember, I said this is the gel casting tray. When we run the test the ends need to be open so the current can pass through the gel. But we need to tape the end until the gel forms into a solid.”

The microwave dings and he removes the measuring cup and pours the melted mixture into the tray. “This’ll take thirty minutes to set up,” he says. “Now we prep the samples.”

While Victor messes around with the buccal swabs and test tubes, I page back in my notebook, reviewing the notes I’ve made. “I had no idea there were so many steps.”

“Fortunately, I don’t have to run DNA every day. But in my lab I have a lot of high-tech stuff that streamlines this process,” he says.

I watch as he uses a drinking straw to pipe the buffering solution into the first two tubes. Then he hands me the straw and I add it to the last two tubes. “So what do you do every day?” I ask.

Victor shrugs. “Solve mysteries any way I can … and go to meetings.” He rolls his eyes. “You have no idea how many meetings. By the way, here’s one for you: Did you know human DNA is 50 percent identical to the DNA of a banana?”

“Is that why bananas are so a-peeling?”

Victor groans and chuckles. “Enough with the puns. That one stunk up the room.”

I laugh along with him, all the while contemplating how this kind of casual, silly, hanging-out fun is what normal families do. But it’s not something that comes naturally to Rachel and me. She’s loving and concerned and protective, but there’s always a barrier. We just never seem to get real with each other. Clearly, Victor’s just being Victor and I’m just being Erin and we’re just here hanging out together, running DNA and making up bad puns. But this feels completely real.

He puts a few drops of dishwashing detergent into one of the test tubes and then plunges the swab up and down, scraping and scrubbing it along the sides of the test tube.

“You’re getting kind of aggressive there.”

“This isn’t a gentle process. In the lab I’d put it in a blender,” he says.

After he’s soaped, scraped, and ravaged all four swabs, he sprinkles a few grains of meat tenderizer into each tube. I pick up the bottle so I can add it to my notes. I can’t resist giving him a strange look. “Meat tenderizer?”

Victor grins. “What is meat?”

I shrug. “Food?”

“It’s protein. In order to run it, we need to free the strands of DNA from the protein. Meat tenderizer destroys protein.” Victor makes an explosive gesture with his hands. “Boom. The DNA is left behind.”

“Wow. You should have been rapping on this stuff in biology today. People might have paid attention.”

“I have analyzed my performance in the classroom at least a hundred times. If I were to do it again I would approach the whole thing differently.” He puts out a hand. “Alcohol, please.”

I retrieve the alcohol from the freezer and set it on the table.

“You’re going to do this part,” he says. “Use the straw and float a small amount of alcohol on top of each of these tubes. By floating, I mean very slowly drizzle the alcohol down the side, so that it doesn’t sink, but floats on top of the buffer.”

I push the bottle of alcohol back to him. “You better do it. I might screw it up.”