Post Number: 54
|Posted on Wednesday, May 20, 2015 - 11:39 pm: ||
Please see information here for details about processing various surfaces.
Post Number: 1
|Posted on Tuesday, April 21, 2015 - 03:59 am: ||
so is all the crime scene processing on TV just science fiction...wishful thinking? The officer didn't do anything to collect evidence. Was he lazy or am I deluded into thinking there is actual science that has advanced fingerprinting beyond slick, hard surfaces only?
Orwellophile (Unregistered Guest)
Posted From: cpe-124-190-249-14.gqle1.lon.bigpond.net.au
|Posted on Tuesday, December 15, 2009 - 09:52 pm: ||
Well, if you watch NCIS - it's highly fictional - but highly entertaining!
As a computer geek, I am used to 99% of all computer scenes in TV and Movies to be totally hollywood.
I would expect nothing different of crime scene analysis, or the more fun things like cell phone tracing, pulling video feeds from random cameras, and "cross checking"...
i'm sure it's all being done somewhere... but not by agencies that have names that you'll see in TV guide.
Post Number: 309
|Posted on Friday, October 31, 2008 - 08:46 pm: ||
Police agencies throughout the US and overseas daily harvest latent prints of perpetrators using crime scene procedures that balance available money/manpower resources for crime scene processing against tolerable destruction of private property.
Often, that means an agency does not send a crime scene team to property crimes (larceny/burglary) of less than a certain dollar value (e.g., $1,000 loss, $5,000 loss, or something higher).
When crime scene technicians do process a typical burglary scene, they often find latent prints of the perpetrator(s) at the point of entry, point of exit and/or elsewhere... even using only a flashlight and fingerprint dusting powder. Envelopes that were torn open or other porous surfaces (that are okay to be destroyed) are typically collected and submitted to a supporting forensic laboratory along with any latent print lifts and/or photographs of latent prints (...and other evidence such as footwear impressions, toolmarks, etc.).
Simple dusting with fingerprint (latent print) powder will miss many latent prints that comprehensive forensic processing (physical/chemical/electronic processing) will develop, but a stolen TV and $5,000 worth of jewelry does not warrant doing $50,000 worth of damage and occupying the house for a week while a crime scene team pours over it.
For who-done-it murders, most agencies pull out all stops and perform extensive crime scene examinations (days or weeks) that may do extensive and costly damage to homes/offices/vehicles processed.
Well-trained police agencies urge officers responding to minor larceny and burglary complaints (below a dollar threshold that triggers sending a crime scene examination unit) to attempt on-the-spot collection of latent print or other forensic evidence. Just using a flashlight (during day or night), the responding officer can often see latent finger/palm prints on smooth surfaces of a door or window at the point of entry. With a simple $30 dollar crime scene dusting kit those point-of-entry/exit prints can be lifted by the responding officer.
If the officer sees latent print marks that do not develop with just dusting (and if he has been trained to know that natural secretions from human fingers are not oily) he can often use the "hut" method to develop such prints. He breathes on the surface and his breath "fogs" the immediate area where he saw the finger/palm marks, then as soon as he sees the fog evaporate, he dusts the area. A slight amount of moisture from his breath adheres to (tags) the latent print residue and causes the powder to stick when he dusts. Before the advent of superglue fuming, the "hut" method (named after the sound of officers breathing hard to fog surfaces) was one of the most reliable techniques for developing prints from natural eccrine gland secretions (eccrine glands are situated in human friction ridge skin covering fingers/toes and palms/soles, and those glands secrete no oils).
Examples of specimens the officer should ask about and collect (if no crime scene unit is responding) include envelopes that were definitely handled by perpetrators to remove money or valuables. Paper is a fine surface for receiving latent prints and there is an excellent chance that the supporting crime laboratory can harvest latent finger/palm prints of the perpetrator(s) if they were not wearing gloves (and even if they wear gloves, they often remove them to open envelopes). Paper envelopes should not be dusted, because eccrine gland secretions are about 99% water and will usually dry by the time the police have arrived, meaning that very few latent prints are recoverable from paper by dusting. Other specimens that offices should collect on-the-spot include shoeprints on papers inside a window at the point of entry, drops of blood if the perpetrator(s) was cut forcing open a screen/window/door.
Adroit officers with a $100 digital camera can practice taking close-up photographs of dimes. Latent print photography is not rocket science and if officers can fill the camera image with a dime in good focus, they can usually do a fine job with those latent prints they may see in dirt on a door or window that was forced open (they should include a small scale, or some small known object [such as the edge of a dime] into at least one of the photos of each print to permit accurate entry and searching of such images into automated fingerprint databases). Conversely, if officers have never practiced photographing a dime, they might be too embarassed in front of the victim to attempt to photograph latent prints.
A little bit of preparation and minimal expense for materials can solve many crimes that will otherwise never be solved because of the dollar threshold limits for when a crime scene unit responds.
Merry Wooten (Kahllie)
Post Number: 2
|Posted on Sunday, October 19, 2008 - 02:24 am: ||
I guess this response to someone else covers my question of why the police did not look for any evidence in the vandalism of my mother's home.
Copy of Response:
Background Details: Unless you often deposit fingerprints in your residence when your hands are contaminated with oil or grease, it is not suprising that dusting found no prints. The friction ridge skin on your fingers, palms, soles and toes include only eccrine glands (sweat glands) which secrete about 99% water and NO oils. After the water in latent finger and palm prints evaporates, the remaining tiny amounts of salt, amino acids, proteins, polypeptides and other solids are not sticky. The water in finger and palm prints secreted from your skin (not from touching popcorn oil, hair oil, etc.) will dry relatively quickly, depending on temperature, relative humidity, the type of surface touched and other factors. When that water has evaporated, there is little or nothing "sticky" remaining in finger and palm prints to hold powder when police dust for prints.
One of the Frequently Asked Questions (click here for FAQs) about finger and palm prints is, "Why didn't the police dust my house (or car) for prints when I reported that thieves broke in?" The answer to that question includes an explanation as to what is normal if the police process your home, and also why you normally do NOT want the police to do everything possible to develop perpetrators' latent finger and palm prints in your home (processing which could cause tens of thousands of dollars in damage to walls, floors, furniture, etc.)
So. The TV shows using sprays and tapes to lift prints, as well as the dusting, and using super glue heated in a chamber to lift prints from porous surfaces, finding hairs that are consistent with physical descriptions of witnessed perpetrators is just a lot of TV Fluff Stuff. A lie. The Discovery Channel portrayal of forensics is also fiction, staged for entertainment, in that case. I'm disappointed to find out that a lot of money is being poured into forensics units and mobile units full of diagnostic equipment that is useful for what? Obviously, it isn't used for collecting evidence (which can't really be collected) if it ever leaves the garage bay.
This just makes me very sad, but it removes any remaining shreds of the false sense of security I had regarding the role and capabilities of the police in the local community.
Ernie Hamm (Unregistered Guest)
Posted From: adsl-153-253-89.jax.bellsouth.net
|Posted on Saturday, October 18, 2008 - 09:38 am: ||
From "Crime Investigation" by Paul L. Kirk:
‘Wherever he steps, whatever he touches, whatever he leaves, even unconsciously, will serve as silent witness against him. Not only his fingerprints or his footprints, but his hair, the fibers from his clothes, the glass he breaks, the tool mark he leaves, the paint he scratches, the blood or semen he deposits or collects. All of these and more bear mute witness against him. This is evidence that does not forget. It is not confused by the excitement of the moment. It is not absent because human witnesses are. It is factual evidence. Physical evidence cannot be wrong; it cannot perjure itself; it cannot be wholly absent. Only its interpretation can err. Only human failure to find it, study and understand it, can diminish its value.’
Your responding officer falls in the category, "Only human failure to find it, study and understand it, can diminish its value."
There are many, many surfaces that can retain recoverable evidence of an associative nature. You are not alone in your frustration; this seems to be an attitude of indifference being experienced in far too many jurisdictions and incidents, major or minor.
Merry Wooten (Kahllie)
Post Number: 1
|Posted on Saturday, October 18, 2008 - 04:14 am: ||
My Mom's house was broken into, and the police were called. The house was vandalized (she was not home), and a neighbour saw a man leaving the house from the front door..the back door was how he got in. I asked if the police would dust for prints..many places in the house were tampered with, including furniture my father made..smooth, varnished surfaces. The policeman told me they would not dust for prints because prints could only be obtained from a hard, slick surface. He said that all that stuff on TV with using crazy glue and such, and getting prints from doors, door frames and knobs, furniture, tablecloths, etc. was just fiction..TV fluff stuff. In real life, it doesn't work that way. It has to be like the enameled surface of an appliance, or porcelain like in the bath.
We found a cell phone in the yard near the back door and gave it to him for tracing numbers of who the person called in order to check their phone records to trace. That isn't real, either.
Is all the crime scene processing on TV just science fiction...wishful thinking? The officer didn't do anything to collect evidence. Was he lazy or am I deluded into thinking there is actual science that has advanced fingerprinting beyond slick, hard surfaces only?