Forensic Processing, Lab Analysis, and Forensic Services (Alabama context)

Processing vs Analysis

  • After evidence is collected, it is sent to the forensic laboratory for analysis.

  • The work performed up to this point is called processing the evidence.

  • Processing includes collecting the evidence in a manner that will allow testing and analysis.

  • Once the evidence reaches the lab, analysis of the evidence begins.

  • In the analysis stage, various tools and techniques are used to identify the evidence (e.g., chemical components of an unknown substance or blood type of a collected sample).

  • The analysis stage also involves comparing the evidence to a known source.

  • Local law enforcement typically handles processing, but many agencies lack the capacity to analyze all the evidence they collect.

  • Therefore, evidence is sent to various crime labs, which may be independent labs or state-run labs.

  • Examples of processing and analysis tasks (from Page 1):

    • Dusting for and collecting fingerprints

    • Identifying key markers on a fingerprint and comparing them to those in a database

From Collection to Analysis: Specific Tasks (Page 2)

  • Collecting blood samples, sealing, and implementing the chain of custody

  • Determining the blood type

  • Taking photos and measurements of gunshot residue on a wall

  • Examining gunshot residue to determine the distance from which the gun was fired

  • Documenting the appearance and location of blood splatters

  • Utilizing blood splatter evidence to determine characteristics of the incident and recreate the scene

Forensic Labs and Workflow (Page 3)

  • There are multiple departments within the forensic laboratory.

  • Evidence is submitted from crime scene investigators to the appropriate lab.

  • The lab provides forms and a kit in which evidence should be collected and submitted.

  • Forensic laboratories are often backlogged and may take several months to process evidence.

  • Information provided about the case upon submission helps the laboratory prioritize cases that need immediate attention.

  • Forensic Services: How states organize their labs differently; example: Alabama Department of Forensic Services (ADFS)

    • Firearm and Toolmark: Examines firearms, ammunition, tools, and related evidence (e.g., gunshot residue).

    • Toxicology: Analyzes biological specimens for presence of drugs and poisons; includes urine and saliva samples collected from living individuals (pre-mortem) and tissue samples collected post-mortem.

    • Death Investigation: Examines human remains to provide information about potential cause of death.

    • Drug Chemistry: Identifies presence or absence of controlled substances and determines the type and amount of drug present in the sample.

    • Fire Debris: Identifies the presence or absence of ignitable liquids within submitted fire debris; in Alabama, this lab is part of the drug chemistry lab.

    • Forensic Biology: Examines samples for the presence of biological fluids and uses technology to determine the DNA profile of the sample and compare it to individuals involved in the case.

  • Other Services Available: Additional services may be available through local jurisdictions, private laboratories, or collaborations with federal labs (e.g., the FBI).

Additional Forensic Services and Roles (Page 4)

  • Fingerprint: This lab may process fingerprints on submitted evidence (e.g., a firearm) or analyze impressions collected by crime scene investigators and compare them to known fingerprints.

  • Electronic Media: Collect, preserve, process, and analyze digital evidence, including computers, mobile devices, and video.

  • Trace Evidence: Identifies and compares trace materials (hair, fibers, fabric, rope, soil, glass, building materials) that could be transferred during a crime.

  • Questioned Documents: Examine written or typed documents to determine authenticity.