Recovering Low-Abundance Biological Evidence: Integrated Air, Surface, and Liquid Workflows for Modern Forensic Investigations

June 30, 2026

Emerging forensic workflows increasingly recognize that biological evidence extends beyond visible samples. Integrating air, surface, and liquid recovery strategies helps investigators maximize the recovery of low-abundance biological material for downstream molecular analysis.

From trace evidence collection to molecular analysis

Forensic investigations increasingly rely on molecular methods capable of detecting and identifying extremely small quantities of biological material. While analytical technologies continue to improve, successful DNA analysis still depends on one critical step that occurs long before the sample reaches the laboratory:

Recovering sufficient biological material from the environment.

Whether evidence exists as airborne particles, trace biological material deposited onto environmental surfaces, dilute liquid samples, or environmental DNA associated with human activity, successful forensic analysis begins with efficient recovery of low-abundance biological targets before downstream molecular testing.

InnovaPrep develops collection and concentration technologies designed to maximize recovery of low-abundance biological material across multiple sample types while preparing samples for molecular analysis.

Why Sample Recovery Matters

Modern DNA analysis methods continue to improve analytical sensitivity, but they cannot detect biological material that is never collected. Sample recovery remains one of the most important—and often overlooked—determinants of successful forensic analysis.

Modern Forensic Evidence Extends Beyond Visible Samples

Traditional forensic evidence collection focuses on visible biological materials such as blood, saliva, tissue, and touch DNA.

However, people continuously release microscopic biological material into their surroundings through:

Respiratory aerosols
Skin cells
Hair fragments
Biological droplets
Environmental DNA associated with human activity

These particles may remain suspended in the air, settle onto surfaces, or become suspended within liquids used during evidence collection or environmental investigations.

As forensic science advances, researchers are increasingly evaluating how these additional sources of biological material may complement traditional evidence collection.

Human activity continuously redistributes biological material throughout indoor environments. Aerosols generated during normal respiration may remain suspended before settling onto nearby surfaces, while contact with people, objects, and environmental features can transfer biological material between matrices. Recognizing these dynamic pathways helps investigators evaluate where evidence may exist, rather than limiting collection to visible biological material alone.

Three Complementary Sample Types

Rather than viewing forensic evidence as isolated sample types, InnovaPrep technologies support recovery across three complementary pathways.

Air

Airborne biological material can provide insight into occupancy, activity, and localized biological sources.

AirPrep™ systems collect biological aerosols onto a dry electret filter before recovering collected material into a concentrated liquid sample using patented Wet Foam Elution™ technology.

Two sampling approaches are supported:

360° Environmental Air Sampling

The standard AirPrep™ inlet continuously samples ambient air from all directions to characterize airborne biological material throughout an indoor environment.

Applications include:

Crime scene assessment
Occupancy studies
Environmental characterization
Human airDNA investigations
General airborne evidence collection

Targeted Point Air Sampling (TPAS™)

Some investigations require investigators to focus on a specific location rather than the room as a whole.

Optional TPAS™ accessories allow directed sampling from:

HVAC vents
Vehicle interiors
Packages
Cabinets
Evidence lockers
Confined spaces
Suspected contamination sources

Together, these approaches allow investigators to perform broad environmental assessment, targeted source investigation, or both during a single investigation.

Airborne evidence should be considered complementary to traditional forensic evidence rather than a replacement. Active aerosol sampling expands the range of potential biological evidence available for investigation by recovering suspended biological material that may not yet have deposited onto environmental surfaces.

Typical applications

Crime scene investigations
Occupancy studies
Indoor airDNA research
Environmental reconstruction
Contamination investigations
Biosecurity

Surfaces

Biological evidence often exists on surfaces in quantities too small to visualize.

Examples include:

Countertops
Workstations
Evidence packaging
Vehicle interiors
Walls
Floors
Equipment
Cleanroom environments

Surface sampling may involve swabs, wipes, rinsates, or large-area recovery methods depending on the investigation.

NASA's planetary protection program helped demonstrate approaches for recovering extremely low levels of biological contamination from large surfaces—an example of how high-sensitivity recovery technologies developed for one application can inform others requiring detection of trace biological material.

Surface sampling remains the foundation of many forensic investigations and complements airborne evidence recovery by capturing biological material deposited onto environmental surfaces. Depending on investigative objectives, recovery methods may include swabs, wipes, rinsates, or validated large-area sampling approaches.

Liquids

Forensic workflows may also generate liquid samples, including:

Surface rinsates
Wipe extracts
Environmental water samples
Process fluids
Laboratory extracts
Rinse water
Extraction buffer
Evidence processing
Environmental waters

Because biological material is often highly diluted within these matrices, concentration prior to molecular analysis can substantially improve downstream sensitivity.

FluidPrep™ CP Select™ concentrates larger liquid volumes into smaller analysis-ready samples while maintaining compatibility with downstream molecular workflows.

The Recovery Workflow

Regardless of sample type, the objective remains consistent:

Collect → Recover → Concentrate → Analyze → Interpret

AirPrep™ performs collection and recovery directly from air.

FluidPrep™ CP Select™ concentrates dilute liquid samples.

Together, these technologies help maximize the amount of biological material delivered to downstream analytical methods including:

STR profiling
qPCR
Digital PCR
Next-generation sequencing
Cell culture
Other molecular and microbiological analyses

Growing Scientific Interest in Airborne DNA

Interest in airborne human DNA has expanded rapidly over the past several years.

Recent publications demonstrate an increasingly sophisticated understanding of airborne DNA recovery and interpretation.

Highlights include:

2022

Detection of human DNA from indoor air sufficient for STR analysis.

2023

Studies examining airborne DNA and settled dust as complementary forensic evidence.

2025

Bibbo et al. evaluated human DNA recovery using the AirPrep™ Cub under varying indoor sampling conditions, demonstrating the influence of occupancy and sampling duration on DNA recovery.

Collectively, these studies suggest that airborne DNA is evolving from an intriguing concept into an emerging area of forensic science.

Emerging Opportunities

Recent studies suggest airborne biological evidence may support:

Indoor occupancy assessment
Environmental reconstruction
Human DNA recovery
Trace biological evidence collection
Source localization
Biosecurity investigations

Importantly, these applications continue to evolve as researchers evaluate factors influencing DNA persistence, transport, recovery efficiency, and forensic interpretation.

Integrated Forensic Evidence Recovery

While individual technologies support different portions of the workflow, the broader opportunity lies in integrating air sampling, targeted source investigation, surface recovery, and liquid concentration into a unified forensic evidence collection strategy.

Rather than viewing air, surfaces, and liquids as independent evidence sources, investigators can use complementary recovery approaches to maximize the probability of recovering low-abundance biological material throughout an investigation.

As molecular analytical methods continue to improve, efficient sample recovery will remain a critical factor influencing overall analytical sensitivity.

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