identification of an individual since it will be prevalent throughout a maternal family tree.”
“Okay,” I struggled to contain my impatience. “So what about the yes and no thing? Which is it?”
“I’m getting to that. As you know, the DNA samples we are working with came from hair. Autosomal DNA, the kind used for positive identification can be extracted from the actual follicles or roots. Using something called polymerase chain reaction, or PCR, the DNA is replicated-or what they call amplified-then separated and compared.
“What they look for are matching alleles at given points in the strand, called loci. The standard for CODIS, the Bureau’s Combined DNA Index System, in order to guarantee the match is thirteen unique loci. Unfortunately, when dealing with degraded samples, the best result they can get is sometimes eight or nine.”
“Not that I don’t appreciate the biology lesson,” I remarked. “But, you still haven’t answered my question.”
“I just want you to understand how this works, Rowan,” she explained. “In Felicity’s case, the samples taken directly from her match exactly on the mitochondrial DNA with all the others. However, of the samples taken from the three crime scenes, there is a variance on the autosomal profile. On one of them there was a full match of the thirteen core markers…”
“Tell me that was the Wentworth homicide,” I said.
She nodded. “Yes, it was.”
“That makes sense,” I offered. “She was actually present at the scene, and it’s entirely possible for her to have lost a hair or two while shooting the photos, especially the way she had to contort herself to get a couple of the shots.”
“Agreed. However, she did have an autosomal match with the sample from the Hobbes crime scene. But, it was only partial and that’s where the variance comes in. On that sample they hit on seven markers. Not all thirteen. The Myrtle Beach sample was only a mitochondrial match, but that was simply because all they had was a small sample of a hair shaft, and no root.”
“Well, then doesn’t that prove it isn’t her?” I asked hopefully.
Constance shook her head. “Not necessarily. Remember, I said this sometimes happens with degraded samples, and that’s what they were dealing with. While it definitely does cast some doubt on a positive match, given the state of the samples, it’s enough for a prosecutor to take to court if there is other supporting evidence.”
“So this is the big secret?” I asked. “Isn’t this something our attorney would be privy to anyway?”
“Eventually, yes. But they are keeping the details under wraps for the moment, at least until they see if there are matching DNA profiles from any of the other scenes that were kicked out by NCIC. In fact, I only found all this out by accident.”
“Accident?”
“Yes. I accidentally saw the results from the lab in DC.”
“Why am I thinking your use of the word accident may be a bit facetious?”
“It’s not my fault the door was unlocked, and the folder was right there on the desk.”
“See what I’m sayin’ about hot water, Row?” Ben chimed, gesturing toward her.
“Yeah,” I replied. “But you would have done the same and you know it.”
“That’s different.”
“Different how?” Constance demanded.
“I dunno, it just is.”
“So, are there actually more DNA profiles?” I queried, pushing the conversation back on subject.
“That’s what we’re hearin’,” he said. “But, truth is we’re both bein’ kept outta the loop a bit.”
“Of course, that’s to be expected,” Constance added. “Given our personal relationships with both you and Felicity.”
“So they’ll use that to their advantage when it is an advantage, but when it’s not…” I said, leaving the rest of the sentence unspoken. I knew Constance would pick up on my inference about her recently being asked to use her friendship with us in an attempt to get information during a jurisdictional turf war between the FBI and local law enforcement.
“Pretty much,” she agreed, without missing a beat.
“Okay, well, this is all well and fine,” I cast my glance back and forth between the two of them. “And, while I appreciate the help, all you’ve really told me is that they have what they consider a smoking gun.”
“Not really,” Ben interjected again.
“Not really, how?”
“Like I said, the match is close, but not positive,” Constance said with a shrug. “That opens things up for a world of doubt. The gun might be warm, but it’s not smoking.”
“Well, I’ve been saying that all along,” I returned. “So, out of curiosity, do you think the samples may have been tampered with?”
“I doubt it,” she said, shaking her head. “Ben told me that was your theory, and while I won’t discount it entirely, I really don’t think it’s likely. Mainly because the easiest way to do that would have been to substitute her hair for the original samples from the unsubs, which would have given a full positive match across the board.”
“Doing that would have been a bit obvious, wouldn’t it?”
“Not really. And, besides, if you’re going to tamper with evidence, you sure don’t want to get too complicated. The KISS principle is usually the best way to keep from getting caught.”
“Okay, but let me ask this. You’re telling me the mitochondrial DNA actually was a full match across the board. I understand it won’t work for positive identification, but isn’t it pretty damning?”
“All it really means is that the killer and Felicity share a maternal link somewhere in their ancestry. That’s not actually as uncommon as you might think, especially when you consider ethnic origin and those sorts of factors. Still, you could be talking about a relative, close or distant.”
I let out a frustrated breath and sat back in my chair. “I’m really afraid all this conversation has done is…”
I wasn’t allowed to finish the sentence. The angry pounding that suddenly issued from my front door didn’t let me.
CHAPTER 19:
The dogs began barking immediately; vociferously defending their territory against the mysterious would be intruder. However, my gut suspicion was that they could bark until they were hoarse, and it wasn’t going to scare away the person on the other side of the door.
“That don’t sound like a very happy knock,” Ben ventured. “You expectin’ company, or did ya’ just piss somebody off?”
Now it was my turn to give an ambiguous answer. “Yes and no.”
“Yeah, and that means?” he prodded.
I was already getting up from my seat. “It means no, I wasn’t actually expecting anyone. Well, not that I invited, anyway. But, yes, I’d say it’s a good bet he’s angry with me.”
“Sounds like you think ya’ know who it is.”
“Judging from the knock, I’d say it’s probably my father-in-law.”
“I’ll bite. Why’s he pissed at you?”
“Other than the fact that he just generally hates me? At the moment, he blames me for Felicity being in jail.”
Constance gave her head a confused shake. “He blames you for this? Why?”
“It’s a long story.”
“Well, if you’d rather not deal with it, I’ll be happy to get the door for you,” she offered.
“No, better let me,” I replied. “If it’s him, there’s no reason for you to be stuck in the middle of a family squabble. I know how you law enforcement types feel about those things, and I don’t blame you.”
The hammering echoed through the house once again, coupled with a muffled shout that sounded something
