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Forensic tech final
forensic tech final
| Question | Answer |
|---|---|
| Admissibility of evidence in Court | Daubert / Frye Standard o Relevance – Probative Value o Reliability / Competency o Meets exclusionary rules ▪ Excludes following: ▪ Heresay ▪ Illegally obtained ▪ Character evidence o Unbiased |
| Reporting Requirements – LiDAR Scanning | Equipment • Make/model • Scanner specifications sheet • Scanner calibration certificate |
| Reporting Requirements | Data collection • Date/time/operator • Scan plan • Total number of scans • Variables specific to scan project (e.g., color/no color; targets/no targets; scanner locations) • Environmental conditions throughout the data capture |
| Reporting Requirements | Technical Terms should be defined and sources cited throughout the report |
| Reporting Requirements | On-site calibration/verification • Reference measurement device used • Reference measurement device certificate (if applicable) • Comparison between scan data vs. reference measuremen |
| Reporting Requirements | Data archival • Data transfer • Hash value generation • Hash comparison • Submission into evidence archive (e.g., property room no. |
| Reporting Requirements | Registration • Registration methods used (targeted, cloud-to-cloud, manual) • Registration results/report: details level of overlap and accuracy between scan positions |
| Reporting Requirements | Post-processing • Filters applied • Data cleanup |
| Reporting Requirements | Final deliverable production • Method for creating final deliverable • Instructions for navigating deliverable |
| Disclosure of Data: Legal Requirements | • Timely and through disclosure of TLS data and reporting • Raw data can be disclosed as soon as practicable • Include Field notes Information Disclosure • Reports or data output should be disclosed at the earliest possible time |
| Reporting Requirements | photo of original, notes to advise context, photo of recovered print on the lift, original digital rendering w/o alterations, final rendering w/ detailed notes outlining enhance, if plotting print & making id supp reports need to be included in disclosure |
| VMD | vacuum metal deposition |
| why use vmd | success when processing aged exhibits that have been exposed to adverse conditions |
| vacuum chamber | removes air molecules, moisture and solvents which allows the metal atoms to travel w/o interference to the surface of the exhibit, w/ no interference the metal atoms retain energy to condense on the surface of the item you are examining |
| Rapid DNA | • Identification ACT • DNA Laboratories ACT • SWGDAM o Mitigate poor case law • Technologist vs Analyst vs Expert |
| Crown and Defense Consults | Attorney understand foundational questions to present evidence effectively in court. If called by crown to testify consultations can be requested. Review notes, evidence, id gaps, highlight tech, If being called by defense, you may review tech & evidence |
| trial prep, scanner operator roles | The operator, tech or analyst must educate the legal professionals regarding the collection, processing, registering and presentation of data. • Operators should be prepared with deliverables or know of equipment, software in advance. |
| testimony, High Level Technical Questions | • Remember to only answers questions within your scope of expertise • Specific questions about how the software / hardware works such as algorithms should be directed to a manufacturer rep for accurate and concise explanations Testimony |
| Testimony | Answer only the q being asked, systematic 'user manual approach', Follow the lead of the crown / defense do not anticipate questions, Take a sip of water instead of 'ums and ahs' Refer to your notes for refreshers ▪ Importance of having detailed notes |
| crime scene documentation | Notes Photography Video Sketches Mapping 3D LiDAR UAV |
| THE USE OF TERRESTRIAL LIDAR SCANNING FOR CRIMINAL JUSTICE APPLICATIONS | Users must be qualified to use the technology, Data gathered must be authenticated, peer Reviewed, demonstrative evidence If intending to use it as a reconstruction, counsel needs to admit it as expert evidence. |
| LEGAL CONSIDERATIONS FOR NEW TECHNOLOGIES - A Judge will decide if the demonstrative evidence is admissible based on: | o Relevance of the demonstrative evidence to the issue o Accuracy in representing the facts o Fairness and absence of any intention to be mislead (unbiased) o Verification on oath by user o Prejudicial effect does not outweigh probative value |
| errors in forensic science | Random vs. Systematic • Accuracy vs. Precision • Measuring Error • Reduce error while measuring • Reporting Error |
| LiDAR | Light detection and ranging |
| laser scanning | Process of capturing millions of data points (to create a point cloud), which produces an unbiased virtual replica of the scene. Data sets can then be used to produce: • 3D models, Maps, Analysis & Reconstructions |
| LASERS | Light amplification by stimulated emission of electromagnetic radiation |
| Lasers | Various light sources can be used as the basis of the laser for LiDAR Infrared Does not interfere with other sensors (cameras, human eye), narrow emission width • Green Light – underwater LiDAR – reduction of scatter (less noise), penetrates further |
| Lidar | Pulsed light emitted, calculating distance either by Time of Flight or Phase Shift calculations |
| how data is captured | Laser pulses emitted collection millions of points’ per revolution. Laser emitted on a 270 ° revolution on axis, while rotating 360° As pulse emits, the return is calculated by either time of flight, or phase shift calculations. |
| how data is captured | Phase shift has a higher accuracy in determining distance.• Each scan is its own entity that then gets ‘stitched’ together at the end of the project. • Panoramic photos are applied to each scan independent of the laser scan data collected |
| Scan plan | Create a plan to know where you’ll be going Create a sketch with rough positioning of your scanner Allows you to visualize what your blind spots will be Acts as a verification that all areas will be covered Can always modify ‘the scan plan’ |
| covering blind spots | 360 coverage • Blind spot diameter below = the height of the machine • Ensure that you’re covering your blind spots • Different heights might be required to fully capture the scene |
| Set up your targets | Targets calibrated for software to ‘lock-in & recognize a unique feature Help provide unique features that allow stitching of scans together. Not always required for indoor scenes, good outdoor scenes Recognize if there are reflective or mirrored surfaces |
| scanning the scene | move scanning through scene according to scan plan , ensure scanner is levelled every time, change parameters as needed, make sure people arent moving through scene, review scan overview after every scan |
| back at office | processing, registration, post processing, court deliverables |
| back at office | Decontaminate equipment • Back-up files • Review Data • Process • Register • Verify Data • Create Court Deliverables |
| Processing Scans | • Setting up the software to create initial data parameters • Stray Point Filters • Distance Filters “To infinity and beyond” • Target Identification • Edge Artifact Filter |
| Registering Scans | • Stitching the scans together • Top – Down / Cloud to Cloud • Geometric Referencing • Target Based Registration |
| Tripod-Mounted Scanners: | High-precision, long-range, durable, ideal for accurate measurements in critical scenes |
| SLAM Scanners: | Portable, field-based devices for large- scale data capture, less focused on high accuracy |
| Handheld Scanners: | Compact, short-range (<2m), ideal for detailed measurements in small areas |
| scanning should be completed after | Photos have been taken • The evidence markers have been placed § Evidence can be picked up prior to scanning to prioritize integrity |
| Scene environment will be a factor dependent on | • Lighting, • Limited space, • Rain, • Fog • and other weather conditions will all dictate scan settings |
| All these factors can affect the overall data gathered | High / low temp can affect instrument’s accuracy, Rain dependent on the instrument’s IP ratings, Rapid Barometric pressure can result in errors in the elevation calculations |
| All these factors can affect the overall data gathered | • Changing environment wind, rain snow you may have capture evidence in a more time effective manner • Considerations for steep slopes |
| Reflective objects can produce artifacts due to reflection or refraction. Multiple ways to prep | A large mirror covered by paper. • Covering a reflective surface with fingerprint powder, aerosol deodorant that contains baking soda and dry shampoo If you are going to alter the scene ensure photos and notes have been made prior |
| Scenes that require precise measurements | require a higher resolution |
| Measurement precision error increases | when the angle between the laser beam and the surface is small (beam is less perpendicular |
| Measurement error decreases | when the laser beam is more perpendicular to the surface |
| Point spacing: | the distance between individual points in the point cloud |
| Critical Measurements: | Point spacing should generally be between 1–3 mm at the location of measurement |
| General Indoor Analysis: | Point spacing should be less than 3 cm at the measurement location |
| General Outdoor Scenes: | Point spacing should not exceed 15 cm at the reference point |
| Scanner Settings: | Operators must ensure point spacing aligns with or exceeds the manufacturer’s guidelines |
| registration defined as | “ the process of determining and applying two or more data sets the transformations that locate each dataset in a common coordinated system so that the data sets are aligned relative to each other |
| Faros file format: | • .fls • .fws • .flw • .pts |
| legal requirements | Timely and through disclosure of TLS data and reporting • Raw data can be disclosed as soon as practicable • Include Field notes Information Disclosure • Reports or data output should be disclosed at the earliest possible time |
| trial prep | • The operator, tech or analyst must educate the legal professionals regarding the collection, processing, registering and presentation of data. • Operators should be prepared with deliverables or know of equipment, software in advance |
| Reconstruction = | Science Uses evidence from the scan to figure out what happened. |
| Recreation = | Illustration Uses the scan to show people what it looked like |
| VMD | low interference with subsequent DNA testing |
Created by:
skyep25