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equipment we didn't have. The best I could do was to use powdered talc.
And of course I'd have to get Genia to take a set of prints off Vlad to verify they were his. I pushed
myself away from my desk and stood up. Horst was tending the hydroponics tanks, Claire was busy
running another gene scan on the sequencer, her display blurry with lines and lines of GCAT. It was a
familiar routine I wished I was still part of, instead of going to get fingerprints from a corpse.
I slapped my forehead. Fingerprints! Gene scan! I'd been wasting my time blundering around in the dark
and the rain when the answer was sitting right in front of me. Everyone has their own DNA, forty-six
chromosomes in twenty-three pairs in every cell of their body, in a pattern unique in the universe save
only for an identical twin. Sperm are a little different, because they only carry half of each chromosome
pair, expecting to mate up with the other half in the egg to form the complete genome of a new offspring,
exactly half of either parent. But for every sperm the genetic pie is sliced in half on a different line, get
enough of them together and they form the same genetic fingerprint as any other cell in the donor's body.
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 Why hadn't I thought of that when I was running around trying to make a crude duplicate of a footprint?
Because I had gotten used to working with amino acids and couldn't work with the genetic code of my
alien plants. Because I wasn't a trained forensic investigator. Because I was tired and stressed and most
of all, because I was, despite all my efforts to the contrary, plainly stupid from time to time. "Claire," I
asked. "Can you do a gene scan on a person?"
"Sure, if you need me to." Her eyes showed concern. She knew where I was going, in outline if not in
detail.
"Could you get a gene scan of everyone in the colony?"
"It depends what you want to know about them. Some factors are easy to link to their genes, some are
quite complex."
"I just need a unique genetic fingerprint for everyone here."
"Yah, I can do that with a few restriction enzymes. It won't give you the actual genome, but everyone's
will be different."
"That's all I need."
"You have some evidence from the autopsy then?"
I nodded. She turned back to her console. "I'll get set up to run it." Her voice was grim.
I found Genia and told her what I'd found last night, which, even if it gave no new evidence, at least
supported the theory that we were dealing with serial rape-murder, and told her that Claire could do a
gene scan. She felt as brain-frozen as I did over not thinking of DNA fingerprinting either. I carefully
looked in the other direction while she took another swab from Mona's body. It's not that I'm squeamish,
but I chose vet medicine over human medicine for a reason.
She took the swab over to Claire while I found Tony. He was over with Syrene, helping with the flitters.
I took him to one side. Everyone else studiously avoided noticing that I'd done it, which only made it
obvious that they had. The tension in our little group was high.
"I need you to call a town meeting. Right now."
His face showed concern. "Why?"
"Genia's found something, the town needs to know about it." It was half-evasive, avoiding my own
participation in the investigation, and avoiding the details of what we'd figured out. I was becoming
increasingly isolated by secrecy, and I couldn't even tell what I should or should not be telling people.
It wasn't enough to satisfy Tony. "Look," he said, his voice carefully reasonable. "If I'm going to disrupt
everyone's work, I have to have a good reason."
I thought about it for a moment. "Mona and Vlad were definitely murdered. Mona was raped as well.
Claire is going to do a gene scan on the whole colony."
Tony's face showed deep concern. "Are you sure about this? Sure enough to stop work?"
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 I looked at him in disbelief. "We have a serial killer on our hands here. Yes, I'm sure." For a moment I
debated telling him of my findings, but they had been completely superseded by the potential of a gene
scan so there was no point. "Yes, I think it's worth pulling everyone in."
My voice had an edge to it and he picked up on it. "Yes, yes of course. There's just a lot to balance
here, you understand. Everyone's overloaded as it is, and I have to look at the big picture."
I nodded. "Thirty minutes in the cargo canopy, okay?"
"The hangar canopy is warmer, and it has lights."
"Even better." I left him there, calling everyone on their coms, and went back to the greenhouse. Claire
and Genia were there, with Horst looking over their shoulders, running the swab sample through
polymerase chain reaction amplification. The criminal's DNA was a gooey white blob in the bottom of the
test tube. I watched as she put it in the sequencer, and five minutes later long strings of genetic code
started flowing over the screen.
Claire smiled. "I wasn't sure if we'd get it or not. What we'll have when we're done here is a combination
of Mona's DNA and the killer's. Then I'm going to run another one with just Mona's and we'll subtract it
out. There'll still be some cross contamination, but since there are only seventeen possible suspects, the
chance of any ambiguity in the result is basically zero.
"Excellent." I put my hand on her shoulder. "Can this run by itself while we have the town meeting?"
"Do I need to be there?"
"We should all be there."
"Okay." We went out, left the sequencer humming quietly to itself.
Tony came by as we went out. "Will hair clippings do to get DNA, Claire? They seem easiest, we don't
want anyone having an excuse to object."
She nodded. "They'll be perfect."
"Okay, I'll go get some scissors, and some plastic bags."
We went to the hangar canopy and waited, watching Syrene's group putting together the flitters while the
other colonists trickled in from whatever jobs we'd interrupted them in the middle of. Quite a few came
by themselves. Tony's buddy system was a good idea, but it simply wasn't practical on a full-time basis
when everyone had so much to get done. Their faces were questioning and the tension was palpable, but
nobody actually asked what the assembly was all about. [ Pobierz całość w formacie PDF ]