ballistics 11

Lecture 11

Explosive detection and anazlysis are critical in

o   Forensic investigations of bombings and attempted attacks

o   Counterterrorism operations and intelligence gathering

o   Public safety screening at airports, government buildings, and events

o   Military operations in conflict zones

Field methods allow for

•       Rapid triage of suspicious materials

•       On-site screening to determine the need for evacuation or further action

•       Preliminary identification to guide safe handling and transport

•       Real-time intelligence for law enforcement and security operations

Challenges in field detection and analysis

Wide variety of explosive compounds

Low vapor pressures of many explosives

Potential interferences from environmental contaminants

Need for high sensitivity and specificity

Importance of proper sampling

Field detection methods

Visual Inspection

-       Colorimetric tests

-       Ion mobilitity spectrometry (IMS)

-       Raman spectroscopy

-       X-ray technologies

-       Portable GC-MS systems

-       FTIR

-       Electrochemical sensors

-       Canine detection units

Collection tools and containers

-       Non-sparking tools

-       Plastic scoops and spatulas

-       Wooden or fiberglass probes

-       Avoid metal tools that could create sparks

-       Anti-static containers

-       Specially designed plastic bags or boxes

-       Conductive containers to prevent static build-up

-       Proper labelling and segregation of samples

-       Unique identifier for each sample

-       Separation of different explosives to prevent cross-contamination

Documentation and chain of custody

o   Exact location (GPS coordinates if possible)

o   Physical appearance (color, texture, form)

o   Estimated amount

o   Surrounding materials or packaging

o   Photographs and sketches of the scene:

o   Overall scene photos

o   Close-ups of the explosive material

o   Scale included in photos for size reference

o   Proper sealing and signing of evidence containers

o   Tamper-evident seals

o   Chain of custody forms initiated

o   Signatures of all personnel handling the evidence

Preservation methods

-       Temperature control

-       Cool storage to prevent degradation

-       Avoid extreme heat or cold that could alter composition

-       Use of preservatives for unstable compounds

-       Stabilizers for nitrocellulose-based explosives

-       Desiccants for moisture-sensitive materials

-       Consideration of volatile components

-       Headspace sampling for volatile organic compounds

-       Use of activated charcoal strips to capture vapours

Sampling of trace explosives

-       Swabbing techniques

-       Vacuum sampling

-       Tape lifting

-       Particle collection

Emerging technologies

Standoff Detection Methods

Nanosensors and Biosensors

DNA-based sensors