jimtrue.com : school : CJT1111 : 2003-06-11: Trace Evidence & Alternate Light Sources (Cont.)
Posted by Jim True on June 11, 2003 6:28 AM. Last Updated October 22, 2006 9:23 PM
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Stokes Shift, energy coming in hitting something, absorbing some of the energy and retransmitting at a lesser energy level, in the Visible light range.
Woods 360 nm Short Wave UV
BlackLight 365-385 nm
Talking about a Black Light and what we've seen with a Black.
Molecular structure level. Nucleus of an atom has Protons/Neutrons surrounded by a cloud of Electrons.
Universal Law of Laziness, also called Ground State. A rock laying on the ground will not do a damn thing, until someone comes a long and kicks it. Natural state to do nothing until acted upon.
Something will stay at the lowest level of energy until acted upon; energy cannot be created or destroyed, just change it's form or mass.
Electron is rotating around the atom just lazily enjoying itself. Bombard Atom with ALS (450 nm) of light. Energy absorbed by the electron, has to go faster. Get's so exhausted, jumps out of the lower orbit into a higher orbit to go twice as fast to burn off some of the energy (same loop, larger circle).
Finally, can't take any more energy it gets rid of the excess energy as a particle of light - photon. After dropping the excess energy, the electron can return to it's regular orbit, it's Ground State. Photon transmitted at a lower energy level than the light waves striking the atoms.
Light coming out a lesser energy level (high nanometers).
Looking at this with a naked eye, all we're going to see is blue, because the blue light is stronger than the light being emitted. We have to use a Barrier Filter to be able to see the light being emitted at a longer wavelength. 550 nm filters (goggles or plate). Blocks everything BELOW 550 (shorter wavelengths below 550).
When TESTIFYING, there's a couple of things you have to know about light. Do not use the word Flouresce or Flourescent or Phosphorence. NO NO NO.
You must use the word LUMINESCE or LUMINESENCE. LUMINESCENCE covers both of these. Flourescent occurs at less than 164,000 thousandths of a second. Phosphorence takes more than 164,000 thousandth of a second. Less than 164,000 thousands (man-made); greater than 164,000 biological.
Lumineses or 'glows'. You MUST know what you're talking about if you start talking technical.
Can't see a firefly during the daytime because Natural Light is more powerful than phosphoresence.
Blood will absorb all light and show as black. Blood under paint, luminol will not react. Blood will absorb light shining through the paint and show up as black spots.
DFO Latent Fingerprint chemical - 570 band pass filter on the machine; 585 barrier filter (red) to look through.
Why don't we use UV light on everything? Too powerful; with the black light the shirt will lumenesce as well. Everything is Stoke's shifting into our visible range.
Fingerprints used flourescent powder that will luminesce at a different wavelength (550, 575, etc.). Fingerprints on a dark surface. Black powder has not contrast.
When does everything luminesce? At it's own certain wavelength.
Red Barrier Filter: 585
Orange Barrier Filter: 550
Yellow Barrier Filter:
When energy is projected into an object and if absorbed, it will re-emit the energy at a weaker wavelength. (Weaker in nanometers means higher number, longer wavelength).
In court, use the baseball analogy. Light is coming in at a high energy, bounces against the surface and absorbs some of the energy and reflects the light back at a weaker energy. Using the barrier filter, I can see the contrast.
Can only see contrast - one thread that glows, or the shirt glows and the thread doesn't. Always say hair or fiber.
Hair grows at about 1/2 inch a month. Once the hair is long, it will grow slower.
Sweat different things from different parts of your body.
Hand soap has alkali in it; alkali eats hair.
A few drugs will luminesce under an alternate light source, several will luminesce at different wavelengths, over 8 pages of 'em.
Laser Wavelength Chart (only showing the visible wavelength).
Luma-Lite - homicide, scan the victim EVERY time. At the scene, and again at the morgue.
Natural/flourescent light - pants stolen out of apartment complex. Recovered a couple of days later. Under ALS, semen showed up quite visibly. Some are gas and oil droplets.
If you're picking up evidence, you should wear gloves. The books says to only wear them when packaging blood stained items; you should wear them all the time.
Tide luminesces, bleach reacts with luminol.
Makeup on a female. ALS - lipstick luminesces.
Double homicide, city of St Pete. Two kids dead in bathtub. Found actual bloody feet impressions on the floor. Two weeks in the back bedroom, found a hair that luminesced. African american hair, dyed red.
One hair solved this case.
Back seat of a car, where your calves would be. Two people in the front side, bullet in the back of the driver's head, passenger has bullet in the side of her head. Searched the car, didn't even open the doors. Scanned on outside with ALS for fingerprints. Searched the seats and found ridge detail with ALS. Under ALS full ridge detail visible. Greases and oils luminesce at their own wavelength.
Hazelhurt case: 86 y.o woman, son is 46 y.o; Son comes home and finds Mom dead in Dunedin. Pinellas worked the scene. Tim Whitfield did the POE; someone took the screen off and opened the window. Found 3 fingers on the window ledge with mag powder.
Bloody fingerprints on the sheet. Tetra menthyl benzadine is what Dave would have worked the scene with - sent to FBI to be worked; they used Amido black, ruined the evidence.
While working the scene, at the Pinellas Co. Recycling facility. 7 bays of garbage. Found the purse of the victim.
House was ransacked before she was killed. Shrink wrap on her face; Cyvek - Cyanoanalyate and dye-stained with M-Star. Fingerprints on MStar with 550 nm ALS.
On the tinfoil surrounding the drugs, used YAG laser and highlighted the ridge detail with the camera on Bulb.
1% of the population or less, their fingerprints will luminesce naturally under the ALS. Riboflavin, B-2.
Altered Check (most cases use IR); under ALS see the differences in the ink.
Jeff Tackett Case: Police officer call on a possible prowler; on his radio 'help, I've been shot it looks bad'.
Prowler was trying to break into an apartment with a girl inside, she called the police. Prowler shot the officer, killed him and escaped down the Pinellas trail.
Shot with a 45 automatic. 3 minutes to bleed out through the femoral artery.
FBI matched glass and paint to the knife used to pry the door and glass.
Next Week read Chapter 11 (we will know Chapter 11 and it will be our friend; also review for Mid term next week).
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