The Institute of Environmental Science and Research (ESR) has changed its name to the New Zealand Institute for Public Health and Forensic Science (PHF Science) as of 1 July 2025. The website address is now www.phfscience.nz. Visitors are automatically redirected to the new address. Please check and update any links and bookmarks.

Tātari ā-Whare Whakawā

Forensic science

PHF Science leads world-class forensic science and research, providing expertise to stakeholders and communities in New Zealand and overseas.

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DNA profiling Forensic scene investigations Reducing drug harm Products Social systems

About

We provide key forensic science services to New Zealand Police and work closely with other agencies, including New Zealand Customs Service and Ministry of Health.

PHF Science is an innovative, globally trusted forensic science organisation, supporting safer communities for all.

Our work serves to ensure fairness and equity in New Zealand's justice and social sectors whilst reducing harm in the community.

We are leaders in drug analysis and intelligence, toxicology, and human biology. Our crime scene investigators work with New Zealand Police and other law enforcement, providing expertise in physical evidence analysis, blood pattern analysis, and DNA profiling.

Through cutting-edge research and development, we apply the latest technology to forensic science. Forensic services developed by PHF Science including Lumi™ Drug Scan and STRmix™ are now making a difference to communities around the world.

An automated method for the generation of bloodstain pattern metrics from images of blood spatter patterns

01 Oct, 2024

An improved automated bloodstain pattern analysis method has been developed and validated, which utilises computer vision techniques to identify bloodstains on a plain background within a digital image.

Reference genes to normalize body fluid identification data obtained using RT-qPCR

20 May, 2024

The use of messenger RNA for body fluid identification has been well documented. While reference genes are commonly used for normalizing gene expression, the use of reference genes in forensic science is not straightforward. Degradation of samples, mixed body fluids, and small volumes contribute to the complexity of normalizing gene expression.

Estimation of population specific values of theta for sequence-based STR profiles

01 Jan, 2024

We describe the estimation of theta (theta) values from autosomal STR sequencing data for five metapopulations. The data were compiled from 20 publications and included 39 datasets comprising a total of 7005 samples. The estimates are suitable for use within the calculation of match probabilities in forensic casework. We also have constructed a phylogenetic tree using this data that aligns with our understanding of human evolution.

A diagnosis of the primary difference between EuroForMix and STRmix

01 Jan, 2024

There is interest in comparing the output, principally the likelihood ratio, from the two probabilistic genotyping software EuroForMix (EFM) and STRmix (TM). Many of these comparison studies are descriptive and make little or no effort to diagnose the cause of difference. There are fundamental differences between EFM and STRmix (TM) that are causative of the largest set of likelihood ratio differences. This set of differences is for false donors where there are many instances of LRs just above or below 1 for EFM that give much lower LRs in STRmix (TM). This is caused by the separate estimation of parameters such as allele height variance and mixture proportion using MLE under H-p and H-a for EFM. This can result in very different estimations of these parameters under H-p and H-a. It results in a departure from calibration for EFM in the region of LRs just above and below 1.

Rapid analysis of amphetamine-type substances using Agilent's QuickProbe gas chromatograph/mass spectrometer technology

01 Jan, 2023

The Agilent QuickProbe gas chromatograph/mass spectrometer (QP-GCMS) is a rapid analytical instrument requiring minimal sample preparation. The instrument was considered for the screening of samples for potential implementation at New Zealand's border screening laboratory. One of the project's primary aims was to validate the method for the analysis of border seizures, including drug concealments, novel psychoactive substances (NPS), low-dose drugs and unknown substances. For the application to be useful beyond the capabilities of current handheld point-of-contact (POC) devices, the initial evaluation has included the analysis of a large variety of compounds in a large variety of matrices. These data will be reported separately. However, during the evaluation, several chromatographical challenges were encountered during the analysis of amphetamine-type substances (ATS). As such, the QP-GCMS required some troubleshooting and method development to improve resolution for this class of compounds.

DNA techniques available for use in forensic casework

01 Jan, 2023

Using DNA to fight crime was unheard of only a few decades ago. The development of DNA profiling revolutionised forensic science and the investigation of crime worldwide. You can find out more about ESR's DNA profiling techniques by reading the DNA techniques available for use in forensic casework..

Uncertainty in probabilistic genotyping of low template DNA: A case study comparing STRMix and TrueAllele

01 Jan, 2023

Two probabilistic genotyping (PG) programs, STRMix™ and TrueAllele™, were used to assess the strength of the same item of DNA evidence in a federal criminal case, with strikingly different results. For STRMix, the reported likelihood ratio in favor of the non-contributor hypothesis was 24; for TrueAllele it ranged from 1.2 million to 16.7 million, depending on the reference population. This case report seeks to explain why the two programs produced different results and to consider what the difference tells us about the reliability and trustworthiness of these programs. It uses a locus-by-locus breakdown to trace the differing results to subtle differences in modeling parameters and methods, analytic thresholds, and mixture ratios, as well as TrueAllele's use of an ad hoc procedure for assigning LRs at some loci. These findings illustrate the extent to which PG analysis rests on a lattice of contestable assumptions, highlighting the importance of rigorous validation of PG programs using known-source test samples that closely replicate the characteristics of evidentiary samples. The article also points out misleading aspects of the way STRMix and TrueAllele results are routinely presented in reports and testimony and calls for clarification of forensic reporting standards to address those problems.

Addressing uncertain assumptions in DNA evidence evaluation

01 Jan, 2023

Evidential value of DNA mixtures is typically expressed by a likelihood ratio. However, selecting appropriate propositions can be contentious, because assumptions may need to be made around, for example, the contribution of a complainant's profile, or relatedness between contributors. A choice made one way or another disregards any uncertainty that may be present about such an assumption. To address this, a complex proposition that considers multiple sub-propositions with different assumptions may be more appropriate. While the use of complex propositions has been advocated in the literature, the uptake in casework has been limited. We provide a mathematical framework for evaluating DNA evidence given complex propositions and discuss its implementation in the DBLRTM software. The software simultaneously handles multiple mixed samples, reference profiles and relationships as described by a pedigree, which unlocks a variety of applications. We provide several examples to illustrate how complex propositions can efficiently evaluate DNA evidence. The addition of this feature to DBLRTM provides a tool to approach the long-accepted, but often impractical suggestion that propositions should be exhaustive within a case context.

Partial validation of multiplexed real-time quantitative PCR assays for forensic body fluid identification

01 Jan, 2023

Confirmatory body fluid identification using messenger RNA (mRNA) is a well-established technique to address issues encountered with conventional testing - such as poor sensitivity, specificity, and a lack of available tests for all body fluids of interest. For over a decade, endpoint reverse-transcription polymerase chain reaction (RT-PCR) assays have been used in forensic casework for such purposes. However, in comparison with real-time quantitative RT-PCR (RT-qPCR), endpoint RT-PCR has lower sensitivity, precision, and linear dynamic range.This research details the multiplexing and partial validation of confirmatory RT-qPCR assays. We have previously described novel assays for a range of body fluid targets and identified an optimal commercial kit for their amplification. Here, multiplexing was undertaken to form three assays: circulatory blood (SLC4A1) and menstrual fluid (STC1), saliva (HTN3) and vaginal material (CYP2B7P), and spermatozoa (PRM1) and seminal fluid (KLK2), all including a synthetic internal control RNA.Partial validation of the multiplexed assays incorporated the MIQE guidelines, ISO requirements, and SWGDAM guidelines. Using receiver operating characteristic (ROC) curves, each marker was significantly different from an uninformative assay and optimal cut-offs were all above 35 cycles. All assays showed a wide LDR (ranging from 3 to 5 logs with most R-2 > 0.99), and high precision (most mean CV < 1 %). STC1 showed some instances of sporadic expression in blood, semen, and vaginal material at high C-T values. CYP2B7P showed off-target expression in semen and blood. The sensitivities were approximated as; saliva: 1 in 1,000 dilution of a whole buccal swab, circulatory blood: 0.01-0.1 L blood, menstrual fluid: 1 in 10,000 dilution of a whole menstrual swab, spermatozoa: 0.001 mu L semen, seminal fluid: 0.01 mu L semen, and vaginal material: 1 in 1,000 dilution of a whole vaginal swab.A total of 16 mock body fluid extract mixtures and 18 swab mixtures were tested and had 100% and 99% detection of target markers below each specific cut-off, respectively. Some mixtures containing high volumes of blood and semen showed off-target CYP2B7P expression. The successful application of a probabilistic model to the RT-qPCR data was also demonstrated. Further work will involve full developmental validation.

Extending the discrete Laplace method: incorporating multi-copy loci, partial and null alleles

01 Jan, 2023

The discrete Laplace method can be used to estimate the frequency of a Y-chromosomal STR haplotype using a random sample from the population. Two limitations of the method are the assumptions that each profile has exactly one allele at every locus and that this allele has an integer repeat number. We relax these assumptions to allow for multi-copy loci, partial repeats and null alleles. We show how the parameters to the extension of the model can be estimated by numerical optimisation using an off-the-shelf solver. Concordance with the discrete Laplace method is obtained when the data satisfy the more stringent assumptions of the original method. We also investigate the performance of the (extended) discrete Laplace method when used to assign match probabilities for haplotypes. A simulation study shows that as more loci are used, match probabilities are underestimated more severely. This is consistent with the hypothesis that the discrete Laplace method cannot model the matches that arise by being identical by descent (IBD). As the number of loci increases the fraction of matches that are IBD increases. Simulation provides support that the discrete Laplace can model those matches that arise from identity by state (IBS) only.

Specialist services

Specialist services

PHF Science forensic experts provide comprehensive consultancy and training services for New Zealand and international clients.

Bloodstain pattern analysis training

 

Bloodstain pattern analysis (BPA) is the science of studying the bloody aftermath of violent crime and accidents to help investigators gather evidence. We provide a range of basic and advanced training opportunities in bloodstain pattern analysis in New Zealand and abroad.

Basic level blood pattern analysis training

About

PHF Science provides Basic BPA training that can be delivered either at our Christchurch Science Centre or at your own facilities, in a course aiming to develop fundamental knowledge about the discipline of BPA, while also growing ability in recognising basic pattern types as building blocks for complex patterns. 

The course is designed for technicians and scientists, research students, and others who require an awareness of BPA science.

 

Purpose

A course designed for technicians, scientists, research students and others who require an awareness of the science of BPA. 

Scope

The course is intended to develop a fundamental knowledge of the discipline of bloodstain pattern analysis and the ability to recognise basic pattern types as building blocks for complex patterns. 

This course will not qualify the trainee to be a bloodstain pattern expert but will equip them to know when an expert is required and how to work with an expert to get the best results from a bloodstain pattern analysis in the laboratory or at a scene. To be able to claim this expertise an individual will need: 

  • further training in BPA at an advanced level 

  • training in other related areas of forensic science 

  • experience at crime scenes 

  • experience in the laboratory 

  • experience in the court presentation of such evidence preferably under searching cross examination 

  • an up-to-date familiarity with relevant literature in this field 

  • experience with laboratory reconstruction and other bloodstain pattern experiments 

Course outcomes

Upon completion of this course the trainee will understand and be able to discuss: 

  • the potential evidential value of bloodstain pattern analysis in the examination of a crime scene and exhibits seized in relation to it  

  • the history and advancement of the discipline of bloodstain pattern analysis  

  • the relevant properties of blood as a fluid, with particular emphasis on the formation of drops  

  • the essence of the human circulatory system and how its characteristics can contribute to the creation of bloodstain patterns  

  • how to combine an area of convergence with impact angle to locate the probable area of origin for a given bloodshed event(s)  

  • the limitations and complexities of bloodstain pattern analysis  

  • methods of advanced bloodstain pattern analysis 

 

In addition the trainee will be able to: 

  • recognise key bloodstain patterns and discuss the mechanism(s) by which they are created  

  • estimate the direction of travel and angle of impact of a single drop bloodstain  

  • apply appropriate selection criteria for the sampling of bloodstain patterns for subsequent testing such as DNA analysis and directional analysis.  

  • photograph, measure, sketch and otherwise fully document bloodstain patterns at crime scenes and on individual items in the laboratory  

  • be able to define the basic BPA terminology and use these terms consistently 

Register for this course

If you are interested in training at our Christchurch Science Centre or at your own facility, please contact course facilitator  Ros Rough  by email. 

Advanced level blood pattern analysis training

About

PHF Science provides an online self-paced Advanced BPA training course.  

The course is a combination of assignments, practical exercises and video presentations.  We provide personal feedback on all submissions and can discuss any questions you have about current cases you might be working on. At the end of the training is a mock scene examination and report writing requirement, a written exam, and a mock court exercise in which your scene report forms the basis for your testimony.

Purpose

A course of instruction designed for scientists, research students and others who require advanced level instruction in the science of Bloodstain Pattern Analysis (BPA). 

Scope

The course is intended to build on competencies gained during basic level training. The focus is on the recognition and interpretation of complex bloodstain patterns. 

Course outcomes

Upon completion of this module the trainee will understand and be able to discuss: 

  • How different actions, that might take place during a crime, can lead to characteristic bloodstain patterns 

  • Key research papers in the field of BPA 

  • Case law relating to BPA 

In addition the trainee will be able to: 

  • Analyse and interpret complex bloodstain patterns at crime scenes. 

  • Resolve the chronology of the bloodstains and reconstruct the chain of events where possible 

  • Estimate regions of origin of impact spatter using physical (string), mathematical (tangent) and computer based (directional analysis) methods 

  • Undertake reconstructions, simulations and research to test alternative hypotheses and understand the importance and limitations of modelling exercises 

  • Be able to competently present a written report and verbal testimony to relevant scientific and judicial standards on the analysis of a scene or evidential items where bloodstain patterns are important. 

  • Critically review BPA evidence 

Register for this course

If you’d like to join a course, please register your interest with course facilitator Ros Rough by email.

THE FLUID DYNAMICS OF BLOODSTAIN PATTERN FORMATION TRAINING

About

This 40-hour course will give bloodstain pattern analysts an
understanding of the basic principles of fluid dynamics as
they apply to bloodstain pattern formation.

Download the course brochure.

Purpose

Our aim for the course is to help bloodstain pattern analysts develop greater interpretative skills. We explore the connections between the physical mechanisms that cause blood to leave the body and the characteristics of static bloodstain patterns. We look closely at the properties of blood as a fluid and the physics of blood droplet behaviour.

Scope

We take a practical, hands-on approach. You will work in small groups on a set of experiments, using a high speed camera to capture bloodstain patterns.

Groups will review and analyse experimental data, and prepare and present presentations to the class describing the results.

You will practice making connections between the dynamics of pattern formation and the features of the resultant static bloodstain pattern.

There will also be lectures and class discussions about the principles of fluid mechanics that will help you gain higher-level interpretative pattern recognition skills.

Pre-course assignment

Some pre-course work, including refresher training on
some basic maths and physics, is required before the
course starts.

Course assessment

There are three parts to the course assessment:

  1. Completion of a practical workbook
  2. An oral presentation made on the final day of the course
  3. An open-book, written exam on the fundamentals of fluid dynamics
Course outcomes

After this course you will be able to:

  • describe and explain the critical physical properties of fluids
    describe and demonstrate the differences between blood and other common fluids and how that relates to Bloodstain Pattern Analysis
  • explain the underlying physical mechanisms of the formation of major bloodstain types 
  • relate the observed characteristics of the major bloodstain pattern types to the underlying mechanisms of their formation
  • use video bloodstain pattern analysis source material in the presentation of court evidence or in basic bloodstain pattern analysis training.
Register for this course

If you’d like to join a course, please register your interest with course facilitator Ros Rough by email.

Forensic scene investigations

We provide specialist consulting services relating to vehicles involved in criminal matters. Our expertise covers the identification of vehicle occupants, number restorations, and paint comparisons. 

Forensic scene investigations

Testing & analysis

Testing & analysis services

By being able to identify what’s really in a substance and how much someone has consumed, PHF Science's extensive drug and alcohol testing services help keep individuals and communities safer.

Learn more

Research & Development

Forensic research & development projects

PHF Science's forensic research and development projects combine casework expertise with research excellence to deliver scientific advancements that improve justice outcomes.

The projects we undertake range in scale from multi-year international collaborations, New Zealand-based contestable funding projects, and internally funded research initiatives.  Many of our projects involve collaborating with New Zealand and international universities including the supervision of student internships, masters and PhD level student research projects.

Our research focuses on the impact end of science. We are interested in projects that have the potential to develop new scientific techniques or breakthrough technologies that can be applied to the casework we undertake and the contribution that forensic science makes to our communities. Undertaking research that has real impact is what attracts people to forensic science and to research in this field.

News
Groundbreaking drug detection service co-designed by PHF Science and New Zealand Police rolls out around New Zealand
08 July 2022
News
PHF Science scientists showcase benefits of collaboration for rapid-DNA sequencing
16 December 2020
Case Study
Border to Grave project
14 March 2018
Case Study
Forensic NZ documentary series
01 December 2017
Case Study
Forensic awareness training
20 November 2017
Case Study
Next generation DNA
14 March 2018
Case Study
New Zealand Customs ESR Screening Laboratory
14 March 2018
News
New PHF Science-led project aims to curb harm from Fantasy with on-the-spot test
01 April 2025
News
PHF Science 'Smart Idea' paper-based drug test wins $1 million in research funding
14 October 2024
News
Lumi™ Drug Scan shortlisted for KiwiNet Award
01 September 2023
News
PHF Science's Lumi™ Drug Scan wins major international award
10 March 2023
News
Lumi™ Drug Scan shortlisted for prestigious world police award
02 March 2023
News
Groundbreaking drug detection service co-designed by PHF Science and New Zealand Police rolls out around New Zealand
08 July 2022
News
Lumi Drug Scan passes major milestone
23 July 2021
News
PHF Science scientists showcase benefits of collaboration for rapid-DNA sequencing
16 December 2020
News
PHF Science and Police announce drug-screening solution for frontline officers
30 July 2020
Case Study
New Zealand Customs ESR Screening Laboratory
14 March 2018

Meet some of our forensic science experts

Angus Newton
Angus Newton

Senior Scientist

Chrissy Black
Chrissy Black

Senior Scientist

Heidi Baker
Heidi Baker

Senior Scientist

Helena Rattray-Te Mana
Helena Rattray-Te Mana

Scientist

Jo Bright
Jo Bright

Senior Science Leader

Katrina Betty
Katrina Betty

Senior Technician

Samantha Coward
Samantha Coward

Team Leader