Now, your case has gone to trial. An attorney is seeking to qualify you to provide expert (opinion) testimony. They introduce you, your qualifications, and what you've been asked to do. The judge may or may not declare you to be an expert so that your opinion can be heard.
As a brief aside, your title or job description can vary widely. I've been an analyst, specialist, director, etc. FRE Rule 702, and the similar rule in your state's evidence code, governs your testimonial experience. Here's the bottom line: according to evidence code, you're not an "expert" unless the Judge says so, and then only for the duration of your testimony in that case. After you're dismissed, you go back to being an analyst, specialist, etc. You may have specific expertise, and that's great. But the assignment of the title of "expert" as relates to this work is generally done by the judge in a specific case, related to the type of testimony that will be offered.
A technician generally offers testimony about a procedure and the results of the procedure. No opinion is given. "I pushed the button and the DVR produced these files."
An expert generally offers opinion based testimony about the results of an experiment or test. "I've conducted a measurement experiment and in my opinion, the unknown subject in the video at the aforementioned date/time is 6’2” tall, with an error of ..."
First off, there's two types of guidance in answering this question. The first type, people's experiences, might help. But, then again, it might not. Just because someone got away with it, doesn't make it a standard practice. Just because you've been through a few trials doesn't make your way "court qualified." These are marketing gimmicks, not standard practices. The second type, a Standard Practice, comes from a standards body like the ASTM. As opposed to the SWG's, who produce guidelines (it would be nice if you ...), standards producing bodies like the ASTM produce standards (you must/shall). For the discipline of Forensic Multimedia Analysis, there are quite a few standards which govern our work. Here's a few of the more important ones:
- E860-07. Standard Practice for Examining And Preparing Items That Are Or May Become Involved In Criminal or Civil Litigation
- E1188-11. Standard Practice for Collection and Preservation of Information and Physical Items by a Technical Investigator
- E1459-13. Standard Guide for Physical Evidence Labeling and Related Documentation
- E1492-11. Standard Practice for Receiving, Documenting, Storing, and Retrieving Evidence in a Forensic Science Laboratory
- E2825-12(17). Standard Guide for Forensic Digital Image Processing
Did your retrieval follow E1188-11? Did your preparation of the evidence items follow E860-07? Did you assign a unique identifier to each evidence item and label it according to E1459-13? Does your workplace handle evidence according to E1492-11? Did your work on the evidence items follow E2825-12?
If you're not even aware of these standards, how will you answer the questions under direct / cross examination?
Taking a slight step back, and adding more complexity, you're engaged in a forensic science discipline. You're doing science. Science has rules and requirements as well. A scientist's report, in general, is structured in the same way. Go search scientific reports and papers in Google Scholar or ProQuest. The contents and structure of the reports you'll find are governed by the accredited institution. I've spent the last 8 years working in the world of experimental science, conducting experiments, testing data, forming conclusions, and writing reports. The structure for my work was found in the school's guidance documentation and enforced by the school's administrative staff.
How do we know we're doing science? Remember the NAS Report? The result of the NAS Report was the creation of the Organization of Scientific Area Committees for Forensic Science about 5 years ago. The OSAC has been hard at work refining guidelines and producing standards. Our discipline falls within the Video / Image Technology and Analysis (VITAL) Subcommittee. In terms of disclosure, I've been involved with the OSAC since it's founding and currently serve as the Video Task Group Chair within VITAL. But, this isn't an official statement by/for them. Of course, it's me (as me) trying to be helpful, as usual. :)
Last year, an OSAC group issued a new definition of forensic science that can be used for all forensic science disciplines. Here it is:
Forensic science is the systematic and coherent study of traces to address questions of authentication, identification, classification, reconstruction, and evaluation for a legal context. Source: A Framework to Harmonize Forensic Science Practices and Digital/Multimedia Evidence. OSAC Task Group on Digital/Multimedia Science. 2017
What is a trace? A trace is any modification, subsequently observable, resulting from an event. You walk within the view of a CCTV system, you leave a trace of your presence within that system.
Thus it is that we're engaged in science. Should we not structure our reports in the same way, using the available guidance as to how they should look? Of course. But what would that look like?
Let's assume that your report has a masthead / letterhead with your/your agency's name and contact information. Here's the structure of a report that (properly completed) will conform to the ASTM standards and the world of experimental science.
Unique Evidence Control Number(s)
Chain of Custody Information
Summary of Request
Service Requested (e.g. photogrammetry, authentication, change of format, etc.)
Experimental Design / Proposed Workflow
Limitations / Delimitations
Delimitations of the Experiment
Limitations in the Data
Personnel Delimitations / Limitations
Amped FIVE Processing Report can be inserted here as it conforms to ASTM 2825-12(17).
Results / Summary
Problems / Errors Encountered
List of Output File(s) / Derivatives / Demonstratives
It would generally conclude with a declaration and a signature. Something like this, perhaps:
I, __________, declare under penalty of perjury as provided in 28 U.S.C. §1746 that the foregoing is true and correct, that it is made based upon my own personal knowledge, and that I could testify to these facts if called as a witness.
Now, let's talk about the sections.
The Administrative section.
- You're the examiner. If you have help, or someone helped you in your work, they should be listed too. Co-workers, subcontractors, etc.
- The requestor is the case agent, investigator, or the client. The person who asked you to do the work.
- Every item of evidence must have a unique identifier.
- Every item received must be controlled and it's chain of custody tracked. If others accessed the item, their names would be in the evidence control report / list. DEMS and cloud storage solutions like Evidence.com can easily do this and produce a report.
- What was it that you were asked to do, in plain terms. For example, "Given evidence item #XXX, for date/time/camera, I was asked to determine the vehicle's make/model/year" - comparative analysis / content analysis. Or, "Given evidence item #XXX, for date/time/camera, I was asked to estimate the unknown subject's height" - photogrammetry. Or, "Given image evidence item #XXY-X, retrieved from evidence item #XXY (see attached report), I was asked to determine if the image's contextual information had been altered" - authentication.
- Provide an abstract of the test and the results - a brief overview of what was done and what the results were (with references to appropriate page numbers).
- What tools did you use - hardware / software? You may want to include a statement as to each and their purpose / fitness for that purpose. As an example, I use Amped Five. Amped Five is fit for the purpose of conducting image science experiments as it is operationalized from peer-reviewed / published image science. It's processing reports include the source documentation.
- Your proposed workflow. What will guide your work? Can you document it easily? Does your processing report follow this methodology? Hint, it should. Here's my workflow for Photogrammetry, Content Analysis, and Comparative Analysis. You can find it originally in my book, Forensic Photoshop. It's what I use when I work as an analyst. It's what I teach.
Limitations / Delimitations
- Delimitations are the bounds within which your work will be conducted. I will test the image. I won't test the device that created the image.
- With DME, there are a ton of limitations in the data. If the tested question is, what is license plate, and a macro block analysis determines that there is no original data in the area of the license plate, then that is a limitation. If the tested question is, what is the speed of the vehicle, and you don't have access to the DVR, then that is a huge limitation. Limitations must be stated.
- Personnel issues should also be listed. Did someone else start the work that you completed? Was another person employed on the case for a specific reason? Did something limit their involvement? If the question involves the need to measure camera height at a scene, and you can't climb a ladder so you mitigated that in some way, list it.
- These are the steps performed and the settings used. This section should read like a recipe so that some other person with similar training / equipment can reproduce your work. This is the essence of Section 4 of ASTM 2825. Amped FIVE Processing Report can be inserted here as it conforms to ASTM 2825-12(17).
Results / Summary
- Did you encounter any problems or errors. List them.
- How did you validate your results? Did anyone peer review your work? This can include test/retest or other such validity exams.
- Conclusions - your opinion goes here. This is the result of your test / experiment / analysis.
- List of Output File(s) / Derivatives / Demonstratives
- Examiner (your name here), along with anyone else who's work is included in the report.
- Reviewer(s) - was your completed work reviewed? Their name(s).
- Administrative Approval - did a supervisor approve of the completed exam?