Training

Multimedia Resources from DNA.gov Training

DNA.gov — administered by NIJ — offers free, self-paced online courses that include videos and animations developed with funding from NIJ. You are free and encouraged to use these as a resources in your own classrooms or other work. We ask only that you acknowledge DNA.gov and NIJ as the source.

The videos and animations below are arranged by the course in which they appear. Find animations and videos from:

Forensic DNA for Officers of the Court
DNA: A Prosecutor's Practice Notebook
Collecting DNA Evidence at Property Crime Scenes
Laboratory Orientation and Testing of Body Fluids and Tissues for Forensic Analysis
DNA Amplification for Forensic Analysts
Amplified DNA Product Separation for Forensic Analysts
STR Data Analysis and Interpretation for Forensic Analysts
Population Genetics and Statistics for the Forensic Analysts
Communication Skills, Report Writing and Courtroom Testimony for Forensic Analysts
Advanced and Emerging DNA Technologies and Techniques

Title and Description	Link to Media
From the Course: Forensic DNA for Officers of the Court
Animation Showing Electropherogram Interpretation Interactive animation that goes through each section of an electropherogram — the graphic representation of the separation of molecules by electrophoresis or other means of separation. From the online course Forensic DNA For Officers of the Court	Animation (swf, 115 KB)
Animation Showing How a Profile Is Derived from an Electropherogram Interactive animation that shows details of an electropherogram — the graphic representation of the separation of molecules by electrophoresis or other means of separation. From the online course Forensic DNA For Officers of the Court	Animation (swf, 162 KB)
Animation Demonstrating of Y-STR Inheritance The Y chromosome is found only in males and is inherited in a patrilineal fashion (i.e., from father to son). STR genetic markers present on this chromosome may be used to obtain the genetic profile of the male donor(s) in mixtures of body fluids from males and females. From the online course Forensic DNA For Officers of the Court	Animation (swf, 107 KB)
Animation Showing Hypervariable Regions of the D-Loop in mtDNA The role of nucleotides in mtDNA is to code for genes involved in energy production. However, there are two small, noncoding hypervariable regions that contain DNA information used in forensic testing. From the online course Forensic DNA For Officers of the Court	Animation (swf, KB)
Animation Showing How Mitochondrial DNA Is Inherited One unique characteristic of mtDNA is that it is passed from a mother to her children. A man's mtDNA is inherited from his mother, but he does not pass it on to his children. This maternal inheritance pattern has two important implications in forensic testing. From the online course Forensic DNA For Officers of the Court	Animation (swf, 199 KB)
Animated Example of a Laboratory Report Determining the Major and the Minor DNA Contributor Sometimes an evidence sample contains a large amount of material from one DNA source — the major source — and only a little from another — the minor source. From the online course Forensic DNA For Officers of the Court	Animation (swf, 131 KB)
Animation Demonstrating how DNA Mixtures at a Crime Scene Can Occur Commonly, evidence found at a crime scene will not have just one person's DNA on it but will instead have a mixture of DNA from more than one contributor. From the online course Forensic DNA For Officers of the Court	Animation (swf, 191 KB)
Animation Showing a Sample DNA Laboratory Report with No Results sometimes testing of a sample is attempted but no results are obtained. From the online course Forensic DNA For Officers of the Court	Animation (swf, 104 KB)
Animation Showing and Explaining an Uninterpretable DNA Sample Sometimes no conclusion can be drawn as to whether a known individual is included or excluded as the source of DNA evidence. Inconclusive or un interpretable results may be due to such complicating factors as multiple contributors, contamination, or degradation of samples. Inconclusive or un interpretable results should not be interpreted as an exclusion. From the online course Forensic DNA For Officers of the Court	Animation (swf, 82 KB)
Animation Showing and Explaining Excluded DNA Samples When comparing a known sample to an evidence sample, the donor of the known is excluded as a source of the evidence if the profiles are different. This can either be referred to as an exclusion or a non-match . When an individual is excluded as the source of DNA, it does not necessarily mean the individual was not involved. For example, a true perpetrator who left no detectable biological material will be excluded as a source of DNA. From the online course Forensic DNA For Officers of the Court	Animation (swf, 179 KB)
Animation Showing and Explaining Matching DNA Samples When comparing a known sample to an evidence sample, the donor of the known is included as a source of the evidence if the profiles are the same. This can either be referred to as an inclusion or a match . For more information on an electropherogram see Module 4, Data Interpretation . From the online course Forensic DNA For Officers of the Court	Animation (swf, 119 KB)
How an Electropherogram Is Generated Once DNA molecules have been separated by electrophoresis, the different DNA types must be detected. As a result of the amplification process, the different STR loci are prelabeled with different colored fluorescent dyes. Their respective alleles are detected by a laser that scans across the slab gel or capillary. On a slab gel, this is sometimes seen as colored bands that are captured in a digital image. An electropherogram, which is a recording of colored peaks, is produced on the CE instrument and some slab gel systems. From the online course Forensic DNA For Officers of the Court	Animation (swf, 124 KB)
Animation Showing Allelic Dropout in DNA Profiles on an Electropherogram sometimes forensic evidence samples contain quantities of DNA that are very small. When an analyst tries to copy the DNA using PCR, the result can be an unbalanced representation of the alleles present and in an extreme case can cause allelic dropout. This can make interpretation of the data difficult and may result in an improper reporting of the DNA profile. From the online course Forensic DNA For Officers of the Court	Animation (swf, 157 KB)
Animation Showing and Explaining Partial DNA Profiles Sometimes, a partial match may be detected. This could occur if several of the loci tested are consistent between the evidence and the known, but the remaining loci yield no detectable alleles (this is different from an exclusion in which alleles are detected but are inconsistent). From the online course Forensic DNA For Officers of the Court	Animation (swf, 260 KB)
Animation Showing Homozygous and Heterozygous Genotypes in DNA Profiles There are three possible genotypes for any two alleles. For example, assume you have alleles 'B' and 'b' at a locus; the possible genotypes are BB, bb, and Bb. From the online course Forensic DNA For Officers of the Court	Animation (swf, 261 KB)
Animation Explaining Genotypes Genotype is the he genetic constitution of an organism, as distinguished from its physical appearance (its phenotype). The designation of two alleles at a particular locus is a genotype. From the online course Forensic DNA For Officers of the Court	Animation (swf, 259 KB)
Animation Describing Genes and Loci The genotypes BB and bb are the homozygous genotypes, and Bb is the heterozygous genotype. From the online course Forensic DNA For Officers of the Court	Animation (swf, 251 KB)
Animation Showing How a Child Inherits Genes from its Parents Nuclear DNA is packaged into chromosomes within the nucleus of a cell. Nucleated cells contain 23 pairs of chromosomes (46 total): half inherited from each parent. Notable exception: Each individual sperm contains only 23 chromosomes. Forensic scientists look at multiple sperm, which collectively provide the full complement of 46 chromosomes. From the online course Forensic DNA For Officers of the Court	Animation (swf, 252 KB)
Animation on How the Product Rule is Used to Estimate STR Frequencies The product rule is used to estimate the chance of finding a given STR profile within a population. This is done by multiplying the frequency of each of the genotypes (combination of alleles) found at all loci in the STR profile. From the online course Forensic DNA For Officers of the Court	Animation (swf, 182 KB)
Interactive Animation Showing the Parts of a Sample DNA Laboratory Report National standards exist for reporting DNA analysis, however, laboratories differ as to the information provided in the analytical report. From the online course Forensic DNA For Officers of the Court	Animation (swf, 281 KB)
Animations Explaining Base Pairs and the Double Helix of DNA The structure of DNA is like a ladder with the base pairs forming the rungs of the ladder. The entire ladder is twisted upon itself like a spiral staircase to form the double helix. From the online course Forensic DNA For Officers of the Court	Animation (swf, 92 KB)
Timeline for the History of Forensic DNA Interactive timelines showing significant events in the history of forensic DNA. From the online course Forensic DNA For Officers of the Court	Animation (swf, 108 KB)
From the Course: DNA: A Prosecutor's Practice Notebook
Interactive Scenario on Investigating Cases Using DNA This scenario involves the murder of a young woman in her home. You will be presented a series of scenes leading up to and following the murder. When the scenario finishes, you will be presented with a cross section of the house in which the murder took place and prompted to click on each room and the outside area to identify potential evidence. From the online course DNA: A Prosecutor's Practice Notebook	Animation (swf, 577 KB)
Interactive Scenario on Preparing Cases Involving DNA You will be presented with a group of slides that present information pertaining to several crimes in chronological order. Select each slide to view specific information regarding the impending capture of a serial rapist. From the online course DNA: A Prosecutor's Practice Notebook	Animation (swf, 538 KB)
Interactive Scenario on Special Case Circumstances This scenario involves two cases, one that occurred five years ago and the other last month. You will be presented with an office desk that has a laptop and two case files on it. Click each case file to view the corresponding information. Once you feel as though you have reviewed everything from both cases, click the laptop. From the online course DNA: A Prosecutor's Practice Notebook	Animation (swf, 1,254 KB)
From the Course: Collecting DNA Evidence at Property Crime Scenes
Seven Step Protocol for Securing and Investigating a Crime Scene The seven step protocol discussed is used to secure and investigate a crime scene. This protocol is a general method that may be superseded by individual agency policies. From the online course Collecting DNA Evidence at Property Crime Scenes	Animation (swf, 174 KB)
Video Demonstrating Collecting a Sample from a Smear Collecting a sample from a smear is different from collecting from a thicker stain. From the online course Collecting DNA Evidence at Property Crime Scenes	Video (00:00:44)
Video Demonstrating Collecting a Dry Stain on an Absorbent Surface Collection procedures for dry stains on absorbent surfaces (examples: wood frame and carpet). From the online course Collecting DNA Evidence at Property Crime Scenes	Video (00:00:20)
Video Demonstrating Swabbing Blood Evidence and Collecting a Control Sample on a Nonabsorbent Surface. Collection procedures for wet stains on nonabsorbent surfaces. From the online course Collecting DNA Evidence at Property Crime Scenes	Video (00:00:20)
Video Demonstrating of Swabbing a Wet Stain on a Piece of Wood Collection procedures for dry stains on absorbent surfaces (examples: wood frame and carpet). From the online course Collecting DNA Evidence at Property Crime Scenes	Video (00:00:20)
Video Demonstrating Hair Collection with Forceps and Trace Paper On some surfaces, hairs and fibers can be seen with the naked eye. Through use of clean forceps and paper (i.e., trace paper), the sample can be removed from the surface and placed into a clean piece of paper that can be folded and packaged in a paper envelope. From the online course Collecting DNA Evidence at Property Crime Scenes	Video (00:00:34)
Video Demonstrating Wrapping a Clothing Item Containing Biological Evidence All evidence recovered at a crime scene, or received at or during a crime scene investigation, should be inventoried and packaged to prevent cross-contamination prior to leaving the scene. The package should be marked, as well as the item of evidence, if possible. From the online course Collecting DNA Evidence at Property Crime Scenes	Video (00:00:35)
Video Demonstrating Control Sample Collection Procedure Control samples, sometimes referred to as substrate samples, are swabbings or cuttings from an unstained portion of the surface material near the recovered stain. From the online course Collecting DNA Evidence at Property Crime Scenes	Video (00:00:21)
Video Demonstrating Swabbing a Jewelry Box Collect swabs from handled items that have been moved, like a jewelry box. From the online course Collecting DNA Evidence at Property Crime Scenes	Video (00:00:23)
Video Demonstrating Swabbing Computer Cables When collecting touch evidence, from computer cables in this example, collect as much sample from a single source on a single swab. if the swab becomes very dirty or damaged in the process, use a second swab. From the online course Collecting DNA Evidence at Property Crime Scenes	Video (00:00:44)
From the Course: Laboratory Orientation and Testing of Body Fluids and Tissues for Forensic Analysis
Video Demonstrating Performing a Screening Test for Blood Procedure for conducting a screening test for blood. From the online course Laboratory Orientation and Testing of Body Fluids and Tissues for Forensic Analysis	Video (00:00:39)
Animation Explaining Absorption-Elution Reactions for Blood Typing Absorption-elution reactions are used for blood typing on dried stains. From the online course Laboratory Orientation and Testing of Body Fluids and Tissues for Forensic Analysis	Animation (swf, 119 KB)
Animation Showing Precipitin and Agglutination Reactions The two main types of reactions that are used to identify serological fluids or tissues are the precipitin reaction and the agglutination reaction. From the online course Laboratory Orientation and Testing of Body Fluids and Tissues for Forensic Analysis	Animation (swf, 46 KB)
Animation Showing Isoelectric Focusing Isoelectric focusing uses a soelectro focusing (IEF) where a pH gradient is formed during the electrophoresis and molecules move until the point in the gel at which they carry no charge. IEF produces much sharper bands than slab gel electrophoresis. From the online course Laboratory Orientation and Testing of Body Fluids and Tissues for Forensic Analysis	Animation (swf, 22 KB)
From the Course: DNA Amplification for Forensic Analysts
Animation of the PCR Process The polymerase chain reaction is an enzymatic process analogous to the replication process used by cells to copy their own DNA. From the online course DNA Amplification for Forensic Analysts	Animation (swf, 173 KB)
Animation Showing Identifying Contamination Problems in DNA Samples If contamination is suspected, the first step of the investigation should be to determine where the contaminant profile has arisen. In many cases, it can be traced back to a particular step in the analysis by working backwards in a step-by-step process. From the online course DNA Amplification for Forensic Analysts	Animation (swf, 38 KB)
Animation Explaining "Hairpins" — Intramolecular Hybridization Self-complementarity can lead to stable hairpin formation with just four GC base pairs in the stem and three bases in the loop. If oligonucleotides form hairpins (intramolecular hybridization), they are not available for hybridization to the target regions. Any kind of hairpin structure should be avoided in a primer. From the online course DNA Amplification for Forensic Analysts	Animation (swf, 29 KB)
From the Course: Amplified DNA Product Separation for Forensic Analysts
Animation About Polyacrylamide Gels Polyacrylamide gels have much smaller pore sizes, are generally stronger than agarose gels, and are used to separate smaller DNA molecules. From the online course Amplified DNA Product Separation for Forensic Analysts	Animation (swf, 82 KB)
Animation Explaining Capillary Electrophoresis Capillary electrophoresis (CE) is an effective tool for the separation of a variety of compounds and materials and is used in the medical and scientific communities. CE is also widely used in the forensic science community in areas such as gunshot residue analysis, explosive analysis, drug analysis, and pen inks analysis. From the online course Amplified DNA Product Separation for Forensic Analysts	Animation (swf, 124 KB)
Animation on Fluorescence Animation showing the operation of the FKBIO III Plus — a laser-based imaging system with four-color fluorescence detection. From the online course Amplified DNA Product Separation for Forensic Analysts	Animation (swf, 216 KB)
Animation Explaining Slab-Gel Electrophoresis Animation showing the operation of the FKBIO III Plus — a laser-based imaging system with four-color fluorescence detection. From the online course Amplified DNA Product Separation for Forensic Analysts	Animation (swf, 53 KB)
From the Course: STR Data Analysis and Interpretation for Forensic Analysts
Animation Explaining an Inclusion or Match Using an Electropherogram An inclusion or match is reported when all the loci from which a result is obtained match between a questioned sample and a known sample. From the online course STR Data Analysis and Interpretation for Forensic Analysts	Animation (swf, 119 KB)
Animation Explaining a Non-Match Using and Electropherogram An exclusion or non-match is reported when loci from which results are obtained are discordant between a questioned sample and a known. From the online course STR Data Analysis and Interpretation for Forensic Analysts	Animation (swf, 179 KB)
Animation Explaining an Inconclusive Result Using and Electropherogram There are occasions when an analyst cannot interpret data or the data is inconclusive. Some mixtures may be too complex to render conclusions and will be reported as uninterpretable. Low-level and/or degraded DNA samples may result in inconclusive results at some or all loci. From the online course STR Data Analysis and Interpretation for Forensic Analysts	Animation (swf, 82 KB)
Animation Showing No Result from a Sample Using an Electropherogram No results are reported when there is no discernable allelic activity observed at a locus. From the online course STR Data Analysis and Interpretation for Forensic Analysts	Animation (swf, 140 KB)
Animation Showing How a Known Contributor Sample Can Be Used to Infer the Profile of an Unknown Contributor to a Mixture It is common to obtain samples where one of the contributors (e.g., the victim) is known. In these cases, it may be possible to infer an unknown profile by subtracting the contribution of the known donor from the mixed profile. From the online course STR Data Analysis and Interpretation for Forensic Analysts	Animation (swf, 109 KB)
Animation Showing Major and Minor Contributors to a Sample The presence of major and minor contributor(s) is distinguishable when samples display alleles that have distinct contrast in signal intensities. From the online course STR Data Analysis and Interpretation for Forensic Analysts	Animation (swf, 131 KB)
Animation Showing an Example of the Stochastic Effect Stochastically induced heterozygote imbalance may be observed in STR analysis due to the effective low copy number of DNA templates in degraded DNA. From the online course STR Data Analysis and Interpretation for Forensic Analysts	Animation (swf, 162 KB)
Animation Explaining Partial Profiles Sometimes when a DNA sample is particularly weak or degraded, only some of its alleles yield visible peaks after amplification, but those that do, match alleles in the sample to which it is being compared. From the online course STR Data Analysis and Interpretation for Forensic Analysts	Animation (swf, 265 KB)
Animation about the Basic Components of an Electropherogram An electropherogram is the graphic representation of the separation of molecules by electrophoresis or other means of separation. From the online course STR Data Analysis and Interpretation for Forensic Analysts	Animation (swf, 114 KB)
Animation Showing Examples of How Mixtures Might Exist on a Piece of Evidence Commonly, evidence found at a crime scene will not have just one person's DNA on it but will instead have a mixture of DNA from more than one contributor. From the online course STR Data Analysis and Interpretation for Forensic Analysts	Animation (swf, 191 KB)
Animation About How Profiles Are Derived from Electropherograms To help analysts more easily derive useful information from the electropherogram, profiling software determines the number of STRs represented by each peak and labels them accordingly. From the online course STR Data Analysis and Interpretation for Forensic Analysts	Animation (swf, 167 KB)
From the Course: Population Genetics and Statistics for the Forensic Analysts
Animation Demonstrating Natural Selection Under natural selection, some individuals in a population have modifications that allow them to more successfully survive and reproduce, making their adaptations more common as a whole due to their increased reproductive success. From the online course Population Genetics and Statistics for Forensic Analysts	Animation (swf, 50 KB)
Animation Demonstrating Linkage Equilibrium Linkage is the tendency of genes or other DNA sequences at specific loci to be inherited together as a consequence of their physical proximity on a single chromosome. From the online course Population Genetics and Statistics for Forensic Analysts	Animation (swf, 57 KB)
Lecture on Paternity Calculations Lecture by Gregory LaBerge, Scientific Director and Bureau Commander, Denver Police Department, on paternity calculations. From the online course Population Genetics and Statistics for Forensic Analysts	Video (00:02:15)
Lecture on Paternity Indexes Lecture by Gregory LaBerge, Scientific Director and Bureau Commander, Denver Police Department, on paternity indexes. From the online course Population Genetics and Statistics for Forensic Analysts	Video (00:03:45)
Lecture on Alleles with Low Frequencies Lecture by Gregory LaBerge, Scientific Director and Bureau Commander, Denver Police Department, on alleles with low frequencies. From the online course Population Genetics and Statistics for Forensic Analysts	Video (00:05:00)
Lecture on Determining the Genotype Frequency Lecture by Gregory LaBerge, Scientific Director and Bureau Commander, Denver Police Department, on determining the genotype frequency. From the online course Population Genetics and Statistics for Forensic Analysts	Video (00:02:52)
Lecture on Confidence Intervals Lecture by Gregory LaBerge, Scientific Director and Bureau Commander, Denver Police Department, on confidence intervals. Confidence intervals are the estimated range of values (calculated from a given set of sample data) that is likely to include an unknown population parameter. From the online course Population Genetics and Statistics for Forensic Analysts	Video (00:01:32)
Lecture on Estimation Lecture by Gregory LaBerge, Scientific Director and Bureau Commander, Denver Police Department, on estimation from a sample of the population. From the online course Population Genetics and Statistics for Forensic Analysts	Video (00:02:13)
Lecture on Statistical Probabilities Lecture by Gregory LaBerge, Scientific Director and Bureau Commander, Denver Police Department, on statistical probabilities. From the online course Population Genetics and Statistics for Forensic Analysts	Video (00:01:47)
Lecture on the Impact of Inbreeding on Statistical Calculations for DNA Analysis Lecture by Gregory LaBerge, Scientific Director and Bureau Commander, Denver Police Department, on the impact of inbreeding on statistical calculations for DNA analysis. From the online course Population Genetics and Statistics for Forensic Analysts	Video (00:03:20)
Lecture on Genetic Drift Lecture by Gregory LaBerge, Scientific Director and Bureau Commander, Denver Police Department, on the impact of inbreeding on statistical calculations for DNA analysis. From the online course Population Genetics and Statistics for Forensic Analysts	Video (00:01:56)
Lecture on Random Mating Lecture by Gregory LaBerge, Scientific Director and Bureau Commander, Denver Police Department, on random mating. Random mating implies that mating should be arbitrary with regard to the locus being considered. From the online course Population Genetics and Statistics for Forensic Analysts	Video (00:04:06)
Lecture on Population Databases Lecture by Gregory LaBerge, Scientific Director and Bureau Commander, Denver Police Department, on population databases. Population databases allow for estimations of how rare or common a DNA profile may be in a particular population. From the online course Population Genetics and Statistics for Forensic Analysts	Video (00:00:47)
From the Course: Communication Skills, Report Writing and Courtroom Testimony for Forensic Analysts
Challenges of Communicating as an Expert Witness Presentation skills are difficult for an analyst to master. The ability to balance the highly technical field of expertise while ensuring the jury comprehends the content is not as easy as one would initially think. From the online course Communication Skills, Report Writing and Courtroom Testimony for Forensic Analysts	Video (00:00:26)
Meeting with Attorneys Before Trial The failure to prepare adequately for courtroom testimony can lead to disaster. Pretrial preparation begins upon receipt of the case. Ensuring that complete, accurate, and legible case file notes are documented will dramatically reduce the amount of pretrial preparation required and, most likely, the amount of time that the witness will remain on the stand. From the online course Communication Skills, Report Writing and Courtroom Testimony for Forensic Analysts	Video (00:00:35)
Example of Cross-Examination Opposing counsel is afforded an opportunity to "cross-examine" the witness. Although these questions are permitted to be leading, they are limited to the scope (or confines) of the direct examination subjects covered. The judge may grant wide latitude of the actual scope during cross-examination with the hopes of shortening the expert's time on the witness stand. From the online course Communication Skills, Report Writing and Courtroom Testimony for Forensic Analysts	Video (00:00:56)
Attorney Proffering an Analyst as an Expert Witness The attorney who calls a witness to the stand proceeds with a line of questions designed to establish the qualifications that are sufficient for the court to accept them as an expert in their particular field. The attorney, at the conclusion of his qualifying questions then "proffers the witness" as an expert in the field. From the online course Communication Skills, Report Writing and Courtroom Testimony for Forensic Analysts	Video (01:01:12)
From the Course: Advanced and Emerging DNA Technologies and Techniques
Robot Preparing Forensic DNA Samples A robot in a forensic DNA laboratory prepare samples for electrophoresis. From the online course Advanced and Emerging DNA Technologies and Techniques	Video (00:00:24)
Robot Transferring Samples from One Machine to Another A robot in a forensic DNA laboratory moves samples from one machine to another. From the online course Advanced and Emerging DNA Technologies and Techniques	Video (00:00:45)