I spent the five happiest years of my life in a morgue. As a forensic scientist in the Cleveland coroner’s office I analyzed gunshot residue on hands and clothing, hairs, fibers, paint, glass, DNA, blood and many other forms of trace evidence, as well as crime scenes. Now I'm a certified latent print examiner and CSI for a police department in Florida. I also write a series of forensic suspense novels, turning the day job into fiction. My books have been translated into six languages.
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The best surfaces for fingerprints are smooth and glossy: clean glass, porcelain, polished marble. It goes downhill from there. The rougher and more porous a surface is, the less chance of finding prints on it. Also if the surface is smooth but if it's covered with dirt or dust--someone who touches it takes away dust instead of leaving a print. Then people's fingers vary greatly in how much sweat and oil will be on the ridges at any given moment--if they're recently washed, if they have dry skin, there will be less chance of leaving prints. Then the environment the object is in--if it's a cool, protected place with steady temperature and humidity, prints can last for years. If it's exposed to light and heat and varying conditions, a print might not last very long at all. Fingerprints are subject to so many variables that we never make an assumption about whether we'll find them or not.
Oh, where to begin, there are so many.
Okay, #1 biggest: We do not really have a BatComputer! Do you remember the episode where they poured in alphabet soup and it spelled out a message? Real scientific instrumentation does not work that way. We don't have a machine that can accept any type of animal, vegetable, or mineral and tell you exactly what you want to know about it. Instruments might analyze organic material or inorganic material or, like my infrared spectrometer, inorganics but only within certain parameters. For example my atomic absorption spectrophotometer was set up to detect barium, antimony and lead on shooter's hand swabs. The hand could be covered in arsenic and I wouldn't have any way to tell. Materials can be run against a database of similar materials, yes, but databases exist because some lab tech went around rounding up samples of nail polish and created their own. There is no national database of perfume or wall paint or cat food--and even if there was, those items change formula every couple of months. So even if I can easily determine that this fiber is, say, nylon 6,6, there is no database that's going to tell me that it comes from a Halston sweater sold only by Macy's and this is how many they sold in this area and this is who they sold them to and, oh, here's a driver's license photo. Companies do not publish their formulas and stores do not hand out their sales figures (and we certainly cannot 'hack in' and get them). That would most likely be violating SEC and civil liberty laws. Okay, enough of that rant.
#2: Someone like me in Smalltown, Anystate, cannot scan in a latent fingerprint (from a crime scene) and search everyone who has ever been fingerprinted in the entire United States including job applicants and military. Most databases are local, maybe statewide depending on where you are and your software. I can search people arrested in my town, and have been receiving those from the county for a number of years. I do not have access to job applicants, not even our own, and certainly not military. That said, I estimate that in five to ten years I will be able to electronically submit a limited number of latent prints to the FBI's national database, but certainly not yet and certainly not for the past 50 years, as TV shows would have you believe.
Those are the two biggest. Oh, and we very rarely package evidence in plastic, we don't wear skin-tight, designer clothes and high heels to crime scenes (when you work around blood, bleach, dirt and decomp fluid you never wear anything that you'd be upset about if it got ruined), we don't interview suspects or tell the cops who to arrest, and we're not all young, single, sexy and angst-ridden. We're really very ordinary. Though I understand that doesn't make for the most captivating TV character.
That probably depends on the person, but in general I'm sure we like cases best when we can discover or determine useful facts that help in the investigation. It's not much fun to process a pile of evidence or do hours of work that ultimately (as most of it does) doesn't make much difference to determining or proving who did it. Homicides are, of course, the most high-profile but they also seem to arrive at the most inconvenient times and require hours and hours of working without a break. Personally I'm probably a little happier to solve a criminal mischief than anything else, because they're so petty and pointless--just stupid kids with nothing better to do than be wantonly destructive! At least a burglary has a logical goal. A selfish, inconsiderate goal, but a goal.
This is certainly possible, but would be a very iffy way to frame someone. First you have to talk this other person into cooperating while you make a mold of their finger. THen you can use some epoxy based putty to cast the finger. Provided this goes well the pattern should be an exact duplicate, so that's good. Now you have to coat that with something to form a fingerprint. Don't use your own sweat and oils in case we do touch DNA on the print. On CSI they used cooking oil spray, which might work but depending on how long or short it is until the print is processed, it might be too soft and just smear when the tech powders it. Then you have to put this cast finger to a piece or pieces of evidence that you are SURE the crime scene tech will print. This is where it gets tricky. Say you stage a break-in and you put it on the window frame or broken glass. Maybe the frame is too rough to hold a decent print, maybe the tech fingerprints 15 pieces of broken glass and then gives up. Maybe you take great pains to put it on the murder weapon and then a traumatized witness or a clumsy tech smudges the print when they pick it up. Maybe you leave it on a note in the victim's pocket (paper is also very iffy!) and then EMS cuts the shirt off and leaves it in the driveway or throws it out in the ER or it gets soaked in blood. THEN when the tech lifts the print, it needs to look consistent with the 'background' from the item and the manner in which it was gripped. Of course if the rubber flakes off into the print that might get more attention than you want. THEN if we decide to do DNA analysis on the print (which is possible even after it's been processed with powder or superglue) the DNA results might be utterly negative or show animal strains (?) or whatever. Again, that might raise a red flag with an analyst, or they might simply figure that there wasn't enough sample to get a profile. So you MIGHT get away with it. Or you might not.
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I'm not into the macabre (I don't have skull earrings and I don't watch zombie movies...unless Shaun of the Dead counts because I love Simon Pegg) (nothing against zombie movies, just don't seem to catch them) and the only thing I appreciate about the dead is that they're quiet and they don't give me a hard time. I've always been into detecting, is the thing. The problem is I wanted to be a detective like Ellery Queen, work my own hours and then just call everyone into the library once I've figured it out. But I never wanted to be a cop and have to deal with stressed-out people, so being a detective was never really an option. A CSI is just unusual enough to be interesting but just routine enough to keep my inner homebody/bookworm/wallflower self comfortable.
Um...no. I've cleared many people but before they were convicted--just routine stuff during the course of an investigation. Of two cold cases that come to mind, in one the guy recanted his confession and eventually won a new trial so I was re-examining evidence, and then just before the new trial he confessed again and went back to jail. Then in the other case, which was quite old, the descendent sued the state for wrongful imprisonment, but the court found that the state had not acted wrongly and still had every reason to think the guy was guilty and no reason to think he wasn't, so that didn't really change anything, either. Unfortunately many of the other cold cases I've worked on are still cold.
Most people do not leave notes so the absence of a note doesn't really affect things.
Was there any sign of a struggle or forced entry? Is the blood spatter consistent with the position of the body (bearing in mind the injuries--it is possible for people to shoot themselves in the and then be moving around afterwards, it all depends on the power and location of the shot)? Is the injury consistent with a self-inflicted wound (angle, distance). Is there a history of previous attempts, depression or problems?
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