shen
Uploaded by
9 SLIDES
260 VUES
90LIKES

Understanding Blood Evidence Analysis in Forensic Science

DESCRIPTION

This guide explores the methods for analyzing blood evidence at a crime scene. It covers visual observations, including the appearance of fresh and dried blood, and the use of luminol to detect hidden blood traces. The importance of documenting the location of blood evidence, collection techniques for wet and dried blood, and the information blood spatter patterns can reveal about a crime is discussed. Key aspects include extraction of DNA, blood type determination, and understanding the angle of blood droplets to infer the source and type of injury.

1 / 9

Télécharger la présentation

Understanding Blood Evidence Analysis in Forensic Science

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Analyzing Blood Evidence Biological Evidence Unit Notes #2

  2. Visual observations: fresh or dried blood should look like blood. • If blood has been cleaned up, traces may still be present • Luminol will make blood visible under UV light • Luminol can contaminate any blood still present • Cleaned traces can identify a crime scene, but cannot be tested as blood evidence Finding Blood Evidence

  3. Document the location of each piece of blood evidence. • Distance from the victim • Large pool or isolated drips • Collect and package each piece of blood evidence separately to prevent contamination. • Dried blood can be cut out, scraped, or lifted with tape (like a fingerprint). • Wet blood can be collected on the original object (if small) or soaked into a sterile cotton pad. • Allow wet blood to dry as soon as possible. Collecting Blood Evidence

  4. Blood type • Extraction of DNA • Blood location • Drips away from victim could be from the attacker • Blood trails • Blood spatter Analyzing Blood Evidence

  5. When blood drips or splashes onto a wall or floor, the drops can tell us about where the blood came from Blood Spatter

  6. If a drop hits the floor at 90° (straight down), it will form a perfect circle • If a drop hits the floor at an angle, the circle will stretch out Angle of Drops

  7. To calculate the angle that the drop came from: • Measure the width and length of the drop • Divide: width/length • Take the inverse sine (sin-1) of the answer • Your final answer should be between 0-180° Width: 2 cm Length: 5 cm 2 cm/5 cm = 0.4 Sin-1(0.4) = 24° Angle of Drops

  8. Length: • Width: • Width/Length: • Sin-1(width/length): Practice

  9. Stab wounds produce large drops, spread out in clumps • Gunshot wounds produce a fine mist, spread out evenly Type of Weapon

More Related