Drippings 12/13/19

Forensic discussion by Richard Bleil

Somewhere, out there, there is a body. I don’t know who it is, and I don’t know how this individual passed away. I don’t even know where, but they are out there, waiting to be found. They might be found in a moment or two, or maybe their body will float downstream after the spring thaw. Maybe they’ll be lost for years. But they are there, waiting.

Whoever this person was, whatever set of circumstances lead them to where they are now, they mattered. They were important to somebody. They were somebody’s spouse, father, mother, child, brother, sister, friend…they had people that cared for them, who loved them. It’s for the ones left behind that they deserve to have their story told, but before it can be told, it must be discovered.

This is where forensic science comes into play. By the time forensic is involved, it’s already too late. The deed is done, the crime committed, the person has already died. But the pieces are there. They are always there, to tell the complete story. They identify the person, they tell if the person died alone, and if not the identity of the other or others that were there, and how this person died. It’s all right there, if the forensic scientist has the skill, experience and technology to find it.

Technology is kind of an interesting aspect of this. Our most advanced technology is nowhere near the abilities of nature. For example, as we walk around, we are dripping chemicals from our body, everywhere that we go. These chemicals, or their ratios, are unique to us. You don’t smell like any other person, and these chemicals linger. We cannot find or detect them instrumentally, but if you need proof, this is how dogs can track individuals. The BBC put together a fabulous story where they took a police dog, and allowed it to smell the clothe worn by the “suspect”. The “suspect” was given an hour head start to wander through the crowded part of London. He went through high traffic areas, and even took the tram, but the dog tracked him down. (The Tram was particularly interesting; at each stop, the dog would get out, smell around, and get back on until it picked the scent back up again.) That dog is smelling the chemicals that we are leaving behind. With a little bit of understanding of the nature of chemicals, one understands that those chemicals will be present forever. Even as they decay away beyond the level that even a dog could detect, they will still be present for years, decades, even centuries.

Of course, another tool, and fairly recent one at that, at the forensic scientist’s disposal is DNA. One of the more interesting stories is of a man who was believed to have raped a woman in Boston in a particularly brutal act. The police really wanted to nail him, and they had the DNA evidence from the victim, but he refused to give a DNA sample himself. They did not have sufficient evidence to get a warrant for it, so were stuck. The years passed, the suspect moved to Los Angeles, and time was running out. As the statute of limitations was nearing, they gave it one more try, and realized that this man had hundreds of dollars of unpaid parking tickets. So, they wrote him a letter saying that they just wanted to clean up their files, and for a nominal fee, they would clear his file of all of the tickets, and even provided a self-addressed stamped envelope. Which he licked. This provided the DNA evidence to convict him.

Today, “touch DNA” evidence is the holy grail of technology. This would allow for enough DNA to be collected from a surface the suspect simply touches, leaving an area no larger than a fingerprint. Today, that technology doesn’t quite exist. DNA evidence, like from the envelop, is too low concentration to be seen by our instrumentation. It has to be replicated in a process that mimics the way DNA is replicated in human cells. Each cycle doubles the amount of DNA from the previous, and each copy is an exact duplicate of the DNA in the sample. They can do this tens of thousands of times until there is enough for them to analyze. The problem is that, if they continue to do so, then trace amounts of impurities of DNA from other sources, or even transcription errors, makes it impossible to analyze. However, finding ways to overcome these errors, coupled with improving the technology so less DNA is required puts this technology on the near horizon.

And with these and other tools, we can bring justice to that person, and give closure to those who loved them.

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