“Don’t worry, Rowan, I understand,” she replied with a nod. “Honestly, clearing Felicity is more important to me too.”
“Okay, so why this secret confab? What is it you know?”
“I’m not entirely sure,” she replied. “But I ran across something that sent up a flag…for me anyway…How much do you know about DNA, Rowan?”
“I know how to spell it,” I replied.
“God, Storm really is rubbing off on you.”
“Yeah, it does seem that way, doesn’t it,” I agreed.
“All right you two, who’s doin’ the pickin’ now?” Ben grunted, but left it at that.
“Actually, I do know the basics,” I spoke up again. “If I remember high school biology correctly, it stands for deoxyribonucleic acid. Everybody has it, and a lot of it is the same, but there’s a part of it that’s as unique as a fingerprint. When it comes to being used as evidence, it can be pretty damaging. Other than that, I know it’s the reason my wife has been taken from me and charged with crimes she didn’t commit.”
“Yeah, well it might interest ya’ ta’ know that when it comes to evidence, there’re a coupl’a different kinds of DNA,” Ben added. “Mitochondrial and autosomal.”
I turned my head, quickly shifting my gaze from Constance and fixing it back on him. His expression was enough to tell me that my own face was showing more than just a little wonderment.
“Don’t look so goddamned surprised, Row. I’m not really as stupid as ya’ seem ta’ think I am. I just let everybody think so.”
“Yeah, okay.”
“Ben’s right,” Constance chimed in.
“Thanks,” he chirped. “About time ya’ stuck up for me.”
“I meant the part about the DNA,” she said.
“What? You think I’m stupid too?”
“Look, I never said you were stupid!” I interjected, a sharp note of exasperation sounding in my voice. “Now, I would really like to get back on subject here…Jail…Felicity…DNA…”
“Ben actually did hit on the point I’m trying to make,” Constance volunteered. “Mitochondrial versus autosomal DNA.”
“Okay, I’ll admit to my own stupidity on this one. I’ve heard the term mitochondrial but that’s about it. I don’t really know what it means.”
“Well, in basic terms, mitochondrial DNA comes from your mother,” she explained. “Autosomal, however, is not gender specific and can come from either the mother or the father. When using DNA for identification, the preferred method is autosomal unless there is no other choice.”
“Why?”
“Because it is where the true DNA profile actually resides. Mitochondrial is not as unique, and it just gets you into the ballpark. Let me give you an example. I inherited my mitochondrial DNA from my mother, she inherited hers from her mother, her mother’s came from her mother, and so on. Since M-T-D-N-A doesn’t change, if you were to compare samples from all of the women in that line, the mitochondrial DNA strand would be identical. No way to distinguish between us.”
“So, you’re telling me the DNA used to ID Felicity is mitochondrial?”
“Yes and no,” she answered. “The problem is that’s the only kind of DNA that can be found in the shaft of hair. While it can be used as evidence in a crime, usually to narrow the field of suspects, it isn’t an absolute 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.”