Archive for the ‘Police Procedure’ Category
DNA testing is a great tool for law enforcement. It’s been used to convict criminals in a wide variety of cases, including, murder, rape, robbery, kidnapping, and even blackmail. DNA testing is also used as a means to exonerate the innocent.
DNA testing is pretty darn accurate as long as investigators and scientists handle crime-scene evidence properly, without contaminating it. Something as simple as sneezing on a piece of evidence can ruin a detective’s chances of solving a homicide.
Every cell in the human body has DNA except red blood cells; therefore, almost anything a suspect handled could contain DNA. Even a hairbrush or hat can contain a murderer’s dandruff. Keeping that in mind, crime scene investigators locate and collect items they think a suspect may have touched—cigarette butts, bloody clothing, weapons, paper, drinking glass, etc. The evidence is then turned over to a forensic lab and its scientists for testing.
At the lab, items are logged in and then they wait on a shelf until their time “on the bench” rolls around. Could be days, weeks, or even months. Wait time depends on the backlog of cases. Of course, some high-profile or other urgent cases warrant a move to the front of the line.
The time to conduct the actual testing is pretty quick, not including prep time, no troubles with equipment, etc.
The first step in the testing process is to extract DNA from the evidence sample. To do so, the scientist adds chemicals to the sample, a process that ruptures cells. When the cells open up DNA is released and is ready for examination.
DNA is actually visible to the naked eye. The slimy glob in the center of the circle below is DNA.
DNA is tested in devices like the one below. They’re called genetic analyzers.
DNA is loaded into wells inside the genetic analyzer. There are 96 wells in the gray, rectangular block shown below (inside the analyzer).
An electric current separates the DNA, sending it from the wells through narrow straw-like tubes called capillaries. During its journey through the analyzer, DNA passes by a laser. The laser causes the DNA loci (a gene’s position on a chromosome) to fluoresce as they pass by, which allows a tiny camera to capture their images.
The image below shows DNA’s path through the genetic analyzer.
Doctor Smith points to the row of eight capillaries, one for each well in the corresponding line of wells (12 rows of 8 wells).
At the end of the testing, the equipment produces a graph/chart called an electropherogram.
Peaks on the graph depict the amount of DNA strands at each location. It is this unique pattern of peaks and valleys that scientist use to match or exclude suspects.
Or, in the case of paternity testing, to include or exclude someone as a parent.
The image below is an electropheragram showing the DNA of a strawberry.
Another method of obtaining DNA results is to “run a gel.” This procedure, like it’s modern day counterpart the genetic analyzer, separates and measures DNA strands.
DNA testing by electrophoresis (gel testing)
Weighing the agar gel (powder at this stage).
Mixing the gel with water.
Gel in chamber. After mixing with water the gel “sets” to the consistency of Jell-O.
Gels are like flat sponges, with many tiny holes, nooks, and crannies.
Injecting DNA into the gel. Pre-formed wells are in place to receive the DNA.
Attaching positive and negative electrodes to the chamber.
Electrical current is the force that causes the DNA strands to move across and through the gel.
Introducing electric current to the gel.
Short strands move quicker and farther than longer strands. Strands of the same or similar lengths wind up grouped together.
Staining the DNA groups makes them visible on the gel. After staining, the completed gel is placed onto an illuminator for viewing.
Gels are then photographed for later use, possibly in criminal or civil trials.
*Above and below photos courtesy of world renowned DNA expert Dr. Dan Krane. Some of you will remember Dr. Krane from his wonderful presentation at the WPA.
DNA is introduced to the testing equipment which then moves through the processes to produce a visible result. It’s not a series of steps where someone could stop, take a look at the incomplete process, and then make a guess as to whether or not someone could be included or excluded as a suspect.
It’s not until the entire process is complete that experts will be able to compare DNA results—suspect DNA to DNA found at a crime scene. Or, to compare test results to human DNA for the purpose of excluding someone as a suspect. There is no midway “make-a-guess-and-leak-to-the-press” point. When it’s done, it’s done.
Below are the DNA test results of a rape victim and two suspects. Obviously, neither of the suspects’ DNA matches that of the victim. However, suspect number two is a perfect match for the DNA found on the victim’s body.
It’s true that excluding someone as a suspect is an often quicker process than identifying the bad guy. This is so because officers already know the identities of some of these people and have collected their DNA samples for testing/comparison.
However, the killer’s identity is probably an unknown at this point because police have not been able to obtain “matchable” evidence from the actual perpetrator. Therefore investigators must begin their quest for a DNA match by conducting good old-fashioned police work—interviewing witnesses and suspects, lifting fingerprints, collecting and identifying physical evidence, and knocking on doors and talking to neighbors, friends, family, etc. Whatever it takes to lead them to the killer and his DNA.
Of course, there’s always the possibility that the killer’s DNA is already tucked away in a computer database, such as CODIS. A quick run-through in the computer system will bring up several close matches, or a positive ID. Remember, though, if the DNA is not in the database investigators must rely on basic investigative skills (please re-read the paragraph preceding this one).
In short, DNA testing is, well, DNA testing. There is no point in the middle of the of the procedure that would allow investigators to exclude anyone as a suspect. The process must run its course to be of use.
*My thanks to Dr. Stephanie Smith for allowing me to hang out in her lab to take the above photos.
Did you know DNA is used to…
Determine pedigree in livestock.
Authenticate caviar and wine.
Identify endangered and protected wildlife species (to prosecute poachers).
A recent news story about the abuse of inmates in some U.S. jails and prisons reminded me of a conversation I once had with a former federal prisoner, a person we refer to as Mr. X.
Mr. X is a former business professional who committed a crime that landed him in federal prison. He’s out now and has shared a few of his prison experiences with the readers of The Graveyard Shift. I contacted Mr. X to see if he’d seen or experienced abuse of any kind at the hand of corrections officers. Here’s what he had to say.
Mr X: I have heard many horror stories of CO’s beating and torturing inmates, but I’ve never seen it. Of course I was locked up in low security facilities my entire time in the system. Things march to a different tune at the higher levels.
But abuse and abusers come in many forms. What devastates one person may be like water on a duck’s back to another. I say this because I’m about to describe some things that happened to me and I’m sure they’ll seem trivial to you, but to me the events were humiliating. Yes, I considered this as abuse. Abuse with no way to stop it.
My abuser was a female CO with jet black hair, a face full of acne scars, and a torso like a tree trunk, complete with arms and legs as limbs. She wore shiny black combat boots and she wore her uniform shirts with the sleeves rolled up to mid forearm. A crude tattoo of a giant scorpion sat halfway between the elbow and wrist of her right arm.
Living quarters in the camp was set up dormitory style. My dorm housed just over 200 men, all in one big room with six-foot-high cinder block walls dividing our two-man cubicles. We all used a common restroom and showers. Both the shower and toilet stalls had individual doors (this was odd because most prisons don’t install doors in restrooms to help prevent hidden activity).
This particular officer, the abuser, made it a point to be in the restroom at the end of the work day when most of the guys were showering. She watched as we removed our clothing or towels. Then she’d walk to each shower door and just stand there gawking. When we turned our backs to the doors she’d order us to face her.
It wasn’t long before she seemed to zero in on me, and that included when I was in a toilet stall. She’d order me to unlatch the door and then she’d hold it open and stand there looking at me until I was done. She was not one bit shy.
I vividly recall staring at her boots, which were only two or three feet away from my feet, while she was there. The toes were incredibly shiny, and slick. I remember thinking about how much time and energy she must have put into getting them that shiny. I thought she must have a military background.
I complained about her to sergeants and her other superiors but they said she was doing her job, watching inmate activity at all times. Funny thing about this was that not one male officer ever, not ever, did either of the things she did. They’d make their rounds, of course. And they’d look to see that all was well and as it should be. But they wouldn’t walk up to your stall and stand there staring at your privates. This woman was downright creepy.
An older prisoner who everyone knew had heart trouble, collapsed on his way to the dining hall. Several inmates ran over to help (there were a couple of medical doctors incarcerated in the camp) but Officer Creepy walked up and ordered the inmates to move away. She announced, “He’s faking so he can get out of work. He can lay there all day for all I care.” And she left him there. An inmate finally ran to the medical department to see if a nurse would help. She did not. A sergeant walked up and Officer Creepy repeated the “faking it” story. He walked on. Eventually an ambulance crew showed up (well over two hours later) and took the man away. He never returned. We later heard that he was DOA when the ambulance crew arrived at the camp to pick him up.
One night I woke up with an excruciating toothache. I spoke to the CO working our building, but he said I’d have to fill out a sick slip to request an appointment to see the dentist, who only visited the camp one day per week. When my appointment finally rolled around, I was sitting in the chair with my mouth wide open, overhead light shining inside, and with the dentist preparing to dig in, when in walks Officer Creepy. She was assigned to guard the medical offices that day. So she comes chair-side and begins to talk to the dentist about how degrading it must be to work on the teeth of a piece-of-s*** prisoner.
The dentist, a retiree and an extremely nice man who treated everyone as people, not animals, told her that he loved his job and he enjoyed helping others who really aren’t in a position to help themselves. For some reason that really set her off. She told him I was faking. He contradicted her saying his exam proved otherwise. She then ordered me to open my mouth really wide. And then, and I couldn’t believe it, she jammed her bare, who-knows-where-it’s-been index finger into my mouth and started forcefully jabbing at my teeth, saying, “Does that hurt? Does it? Well, does it?”
The doctor protested meekly, but she continued her tirade. Clearly she intimidated the frail dentist, and he did nothing to stop her.
When she finished poking around she placed her hand on the side of my face and pushed my head to the side. She ordered me back to the dorm. The dentist pleaded my case to her and she finally consented to let him finish the filling.
One night the officer working our dorm told me to mop and buff the hallway floors in the administrative section of the building. It’s the part of the building where the counselors’ and ranking CO’s office’s are located. There’s no one back there at night. I grabbed the tools and supplies and the CO let me inside. He told me to knock when I was ready to come out. Each of the office areas were securely locked and there was nowhere else to go so it was not unusual for them to lock us inside the hallway to work.
As I was getting ready to begin, an office door opened around the corner. I turned just in time to see Officer Creepy and another female guard come out. Both were adjusting their uniforms and securing buttons. Creepy kissed the other officer on the cheek and turned to head back to the dorm. That’s when she saw me and I prepared myself for a trip to “the hole.” I was certain that she would come up with something that would land me in solitary for a long, long time, just to save her own skin.
However, she surprised me by walking past without saying a word. Nothing. Not even eye contact.
The night passed and nothing happened. I didn’t see her again for at least a week. Then nothing. I never saw her at the camp again. I don’t know if she quit, or what. All I know is that it felt like a huge weight had been lifted from my shoulders. No more “visits” from her.
Like I said, to some these incidents probably seem minor. As far as I’m concerned, though, Officer Creepy was a bully and a sex offender. Sadly, the system supports her type of behavior.