Crime Scene Science: The Modern Methods for Solving Crimes

CRIME SCENE SCIENCE THE MODERN METH ODS FOR SOLVING CRIMES POLICE CSI DA JUDGE EXAMINER DETECTIVE SPECIALIST Every crime scene must pass under the watchful eyes of a host of professionals. Their duties range from the police, who arrive first to secure the area, to judges, who grant search warrants for further investigation. Then there are the forensic specialists, CSIs, and coroners, who dive deep into the gritty details: dusting for prints, finding evidence in every detail of a crime scene, and identifying suspects through DNA evidence. Find out how these specialists turn the wheels of justice with beakers and chemicals instead of gavels and juries. HOW TO LIFT A FINGERPRINT CLEAR TAPE for lifting powders LIFT CARDS MAGNIFIER BRUSHES CHEMICALS POWDERS for porous surfaces metallic or black GLOVES SUPER GLUE for fuming For Non-Porous Surfaces For Porous Surfaces 1. Brush a contrasting color of powder onto the surface where the print is located using a circular motion. 2. Brush in the direction of the skin ridges when the print appears. 3. Press clear tape over the powder to pick up the print and attach the tape to a finger print card of contrasting color. 1. Spray iodine onto the surface of the material to reveal the latent print. If that does not work, apply Super Glue to a metal plate and heat to approximately 120°F. 2. Seal the plate and the object containing the print in an airtight container. The fumes from the Super Glue will reveal the print which is photographed for analysis. ESTIMATING THE TIME OF DEATH BODY TEMP OF time since death: if the body is... 98.6° -2.7°=1 hour Warm and not stiff | Warm and stiff | Cold and not stiff | Cold and stiff 95.9° -2.7°=2 hours х хх хх хх 93.2° -2.7°=3 hours 90.5° <3 hrs 3-8 hrs 8-36 hrs >36 hrs -2.7°-4 hours 87.8° -2.7°=5 hours 85.1° -2.7°=6 hours 82.4° -2.7°=7 hours 79.7° AMBIENT TEMP F 7 hours since time of death FORENSIC ENTOMOLOGY MITES Mites feed on the corpse throughout its decomposition; some types focus on the early stages, while others prefer to feed on dry skin in the later stages. FLIES Flies also arrive early, as maggots prefer a fresh corpse to feed on. Their systems can be analyzed to find any toxins that BEETLES Hide beetles usually approach a corpse after 5 to 11 days. They can also be used to find toxins MOTHS Moths forage on any hair that remains on a body during their larval stages. They are among the last type of insect that add to the process of decomposition. were present in the body before death. and drugs, which is useful for severely decomposed bodies. A dead body attracts many insects, which feed on and lay eggs in corpses. You can learn a lot about a body from these factors: 1the species, 2 the community composition, 3 and the age of the insects. DNA PROFILING DNA evidence must be stored in -ADENINE+THYMINE paper bags or envelopes. Plastic is never used; it retains moisture and can damage DNA samples. CYTOSINE+GUANINE Sets of 2 nucleotides link together in a DNA strand, forming base pairs. The vast majority of human DNA is identical; just .1% of your base pairs are unique to you. The best sources for DNA analysis: Scientists don't need a big sample to do a thorough analysis because they can replicate a small sample artificially, creating thousands of copies. Once this large sample set is made, specific genes can be analyzed to identify an individual. highest DNA concentration - Semen Muscle Tissue (if you had equal amounts of each of these materials, semen would contain the most DNA and hair would contain the least) Bone Blood Saliva Skin Cells lowest DNA concentration - Hair ANALYZING BLOODSTAINS Type of weapon Handedness of assailant Date/time of crime Positions of people/things Types of injuries Bloodstain Pattern Analysis can track the trajectory of blood drops, determining their point of origin and the type of wound. Smaller drops indicate the blood fell a shorter distance. Longer tails show the blood hit the surface at a sharper angle. 1 in 2 ft 4 ft 6 ft 8 ft 90° 70° 50 30° 10° HOW TO DO AN AUTOPSY 1Y-Incision Removal of Organs 3 Stomach Contents 4 Brain Examination 5 Replacement хх Next, the stomach is examined, which shows The pathologist makes an incision across the crown of the scalp to examine the brain when the victim last had a meal. This helps determine the time of After these procedures, when all of the organs The breastplate is cut open to gain access to the body's major organs. The Y-incision cuts from shoulders to sternum, then down the abdomen. inside the head. Then The major organs are then removed and death, as the amount of digestion that has progressed until death can be analyzed to try and narrow down the likely time frame. the brain is removed weighed. Blood and DNA samples are taken, and the heart is tested for any signs of poisoning. for a more thorough inspection. Body-wide tissue samples are also taken, spanning the brain, liver, and eyes. have been placed back into the body, it is sewn up. The samples are taken to a laboratory for further testing. REFERENCES How to Lift a Fingerprint: http://en.wikipedia.org/wiki/Crime_scene_investigator http://science.howstuffworks.com/csi4.htm Estimating the Time of Death: http://library.thinkquest.org/04oct/00206/time_since_death.htm http://www.exploreforensics.co.uk/estimating-the-time-of-death.html http://www.studyworld.com/basementpapers/papers/stack12_14.html Forensic Entomology: http://insects.about.com/od/forensicentomology/p/csibodymoved.htm http://en.wikipedia.org/wiki/Forensic_entomology DNA Profiling: http://science.howstuffworks.com/dna-profiling.htm Analyzing Bloodstains:http://www.forensicnursing.org/forensic-analysis/ How to Do an Autopsy: http://www.exploreforensics.co.uk/performing-an-autopsy.html eLocalLawyers