The search room Flashcards
What does TET stand for?
Trace evidence triage
How should admin and lab work be done?
Separetely
What 2 rooms should there be in the search room?
Complainant (dirty clean room) and suspect (clean clean room)
What are the desirable features of a search room?
Antechamber (small room leading to main one for donning PPE), Separate entry and exit doors with sticky mat, no windows for controlled light and positively pressured filtered air supply, central large (or movable) examination table, peripheral benches for examining small items, access to telephones, cameras, microscopes, presumptive tests and record making consumables
What is the contrast ratio?
CR= Bo-Bb/Bb (brightness of object- brightness of backgroun/ brightness of background)
What does it mean if the contrast ratio is infinity?
The object is brighter than background and increase in light intensity will make it stand out
What does it mean if the contrast ratio is 1?
Object is darker than background and increasing illumination tends to white out image
What are the 4 main techniques used on larger objects?
Handpicking, Tape lifts, Shakings and Vacuumings
What techniques (5) can be used on larger objects?
Sweeping (good for cars), Swabbing, Cutting/scraping, Pipetting and washing, casting
What are the steps for a Hemastix test?
Clean work area and wear PPE and record in notes, check use by date and condition of kit and record, Do a control sample of test strip with water (if +ve discard and start again), apply probe to test strip (if -ve probe is clean), apply swab to red brown stain if test strip changes colour it is +ve response. If nothing happens do a positive control
What are the steps for Luminol?
Solution of H2O2 and hydroxide salt in water is activated by an oxidant and acts as activator. In presence of catalyst (iron), hydrogen peroxide decomposed to oxygen and water. When luminol reacts with hydroxide salt, dianion is formed. Oxygen produced from H2O2 reacts with luminol dianion giving unstable organic peroxide which loses nitrogen. Electrons move from excited state to ground state with emission of energy as photon gives off blue light
What are the desirable features of a presumptive test?
Transportable, safe for operator and environment, sensitive to target, selective, fast and easy to do, based on understood and accepted science, specific, unambiguous result, reaction mechanism explainable, reagents obtainable and inexpensive
What are you overall looking for as a forensic chemist?
Differences not similarities
