Next-Generation Sequencing (NGS)

Forensic Biology and Next-Generation Sequencing together represent one of the most transformative developments in modern forensic laboratory science. NGS, also called Massively Parallel Sequencing (MPS), enables simultaneous sequencing of millions of DNA fragments, providing far more genetic information than conventional forensic DNA typing methods.

Blog Jun 29, 2026 0 8 Add to Reading List

Background: From STR Profiling to NGS

Traditional Forensic DNA Analysis

Conventional forensic DNA typing mainly relies on:

Short Tandem Repeat (STR) analysis
Capillary electrophoresis (CE)
PCR amplification of selected loci

This approach is highly effective but has limitations:

Difficulty interpreting mixed DNA samples
Limited discrimination in degraded samples
Inability to extract ancestry or phenotypic information
Reduced sensitivity for low-template DNA

Emergence of NGS

NGS overcomes many of these limitations by sequencing DNA at the nucleotide level rather than only measuring fragment size.

Core Principle

Instead of analyzing one DNA region at a time, NGS can:

Sequence hundreds to thousands of loci simultaneously
Detect sequence variation within STRs
Analyze SNPs, mtDNA, and epigenetic markers together

2. What Makes NGS Important in Forensic Laboratories?

Key Advantages

Feature	Traditional STR	NGS
Number of markers analyzed	Limited	Very high
Mixture interpretation	Moderate	Improved
Degraded DNA analysis	Limited	Better
Sequence-level information	No	Yes
SNP analysis	Limited	Extensive
Phenotype prediction	No	Possible
Ancestry inference	Minimal	Advanced

3. Major Applications of NGS in Forensic Biology

A. Human Identification

NGS enhances individual identification by analyzing:

STRs
SNPs
InDels
mtDNA simultaneously

Laboratory Significance

Useful in:

Criminal investigations
Missing persons cases
Mass disasters
Human trafficking investigations

B. Complex DNA Mixture Interpretation

One of the biggest forensic challenges is mixed DNA profiles.

NGS Advantage

Sequence-level data can differentiate alleles having identical lengths but different nucleotide sequences.

This greatly improves:

Contributor separation
Statistical interpretation
Minor contributor detection

Research Area

Development of probabilistic genotyping algorithms for NGS datasets.

C. Degraded and Low-Copy DNA Analysis

NGS is highly useful for:

Burned remains
Skeletal remains
Ancient biological samples
Highly degraded crime scene evidence

Why?

NGS can target very short DNA fragments (“mini-amplicons”), improving recovery from damaged samples.

DNA Fragmentation Methods for NGS | Revvity

D. Forensic Phenotyping

NGS can predict externally visible characteristics (EVCs):

Eye color
Hair color
Skin pigmentation
Facial morphology (emerging)

Example

DNA from an unknown suspect may generate investigative leads regarding physical appearance.

Ethical Concern

Potential privacy and discrimination issues.

E. Ancestry and Biogeographical Origin

SNP panels analyzed by NGS can estimate:

Continental ancestry
Population affinity
Migration lineage

This is useful in unidentified human remains cases.

F. Mitochondrial Genome Sequencing

Traditional mtDNA typing analyzes only hypervariable regions.

NGS permits:

Whole mitochondrial genome sequencing
Higher discrimination power
Better maternal lineage analysis

Particularly useful in hair shaft and skeletal analysis.

G. Forensic Epigenetics

An emerging field involving epigenetic biomarkers.

Applications

NGS can analyze DNA methylation patterns for:

Age estimation
Tissue source identification
Lifestyle prediction (experimental)

Current Research

Biological age prediction models using methylation markers.

4. Workflow of NGS in a Forensic Laboratory

Step 1: Sample Collection

Biological evidence:

Blood
Saliva
Hair
Semen
Bone
Touch DNA

Step 2: DNA Extraction

Standard forensic extraction methods:

Organic extraction
Chelex extraction
Silica-based purification

Step 3: Library Preparation

A crucial NGS step.

Includes

DNA fragmentation
Adapter ligation
Barcode/index attachment
Amplification

Each sample receives a unique barcode.

Step 4: Sequencing

Common forensic NGS platforms:

Platform	Company
MiSeq FGx	Illumina
Ion Torrent	Thermo Fisher Scientific
Oxford Nanopore	Oxford Nanopore Technologies

Step 5: Bioinformatics Analysis

This is one of the most important laboratory challenges.

Tasks Include

Sequence alignment
Variant calling
STR interpretation
SNP analysis
Statistical calculations

Emerging Need

Dedicated forensic bioinformatics pipelines.

Step 6: Interpretation and Reporting

Laboratories must validate:

Accuracy
Reproducibility
Sensitivity
Contamination thresholds

before courtroom implementation.

Biotechnology – Introductory Biology

5. Emerging Research Areas in NGS Forensic Biology

A. AI-Assisted NGS Interpretation

Machine learning for:

Mixture deconvolution
Sequence classification
Error correction

B. Portable Sequencing

Devices like portable nanopore sequencers may enable:

Crime scene sequencing
Field-based disaster victim identification

C. Single-Cell Forensics

Analyzing DNA from individual cells in mixtures.

A highly advanced future direction.

D. Multi-Omics Forensics

Combining:

Genomics
Transcriptomics
Proteomics
Metabolomics

for comprehensive forensic profiling.

Importance of Optimizing Your NGS Workflow

6. Challenges in Forensic Laboratories

Technical Challenges

High instrument cost
Complex data interpretation
Large data storage requirements
Need for specialized bioinformatics expertise

Validation Challenges

Forensic methods require strict validation:

ISO/IEC 17025 compliance
SWGDAM guidelines
Reproducibility studies

Legal and Ethical Issues

Major Concerns

Genetic privacy
Population bias
Predictive phenotyping ethics
Database misuse

Courts require transparency and scientific reliability.

7. Important Bioinformatics in NGS Forensics

Common Analytical Areas

FASTQ data processing
Variant calling
Alignment algorithms
STR sequence analysis
Bayesian statistical interpretation

Relevant Software

STRait Razor
ExactID
EuroForMix
GeneMapper (hybrid workflows)

Bioinformatics is becoming central to forensic laboratory operations.

Introduction to DNA Sequencing - Geneious

8. NGS vs Traditional STR Typing

Parameter	STR-CE	NGS
Resolution	Fragment length	Full sequence
Throughput	Moderate	Very high
Mixture analysis	Limited	Improved
SNP capability	Minimal	Extensive
mtDNA sequencing	Partial	Whole genome possible
Data complexity	Lower	Very high
Cost	Lower	Higher