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Advertorial: How to ensure that your video and image evidence can stand up to questioning?

David Spreadborough, Forensic Analyst at Amped Software provides the answer.

Advertorial: How to ensure that your video and image evidence can stand up to questioning?

Date - 28th February 2022
By - David Spreadborough

An officer once told me that his unit hated dealing with CCTV evidence as it was so problematic. They did use other words but I’ve toned it down a little. I, on the other hand, enjoyed the challenges that it brought and it’s been nearly 20 years since I started a Force’s CCTV Unit. After 24 years as an officer, however, I left in 2015 to keep helping others with their video evidence. 

Even though time has brought tremendous change, with not all of it good, there have been some common themes through the years and their importance have been recently raised with increased scrutiny in the reliability of video and imagery evidence. 

The questions surrounding the accuracy of the visual image were intended to be solved with the introduction of standards in CCTV Investigation and Forensic Video Analysis. However, as is common in the legal world, these have brought with them some confusion and ambiguity. 

So, to make things easier, let us move those to one side for a moment and look at a more simplistic approach to trusting the video and image evidence.

  • Integrity
  • Authenticity
  • Validity

If your evidence has all three, then it should be admissible and can be trusted as reliable evidence. 

Integrity 

Integrity examines the question of what has changed since the item was first created. Ensuring no changes, or identifying and documenting changes is of paramount importance in a world where digital media can be altered and misinterpreted so easily. 

The most important stage is the acquisition of the first recording. Any changes to that file will affect its ability to answer the questions being asked of it, and therefore perhaps reduce the exhibits weight within an investigation.

If a changed copy is first obtained to proceed with an investigation quickly then the original recording must be acquired as soon as practicable to ensure that there is an integrity chain between them. 

As an example, it is quite acceptable to initially obtain a screen snap of a suspect for the initial, and immediate, release to the press to identify and trace a dangerous suspect. It may not be the best quality but maybe enough to assist in early recognition and apprehension of the suspect. When there is no immediate risk to the public then it is best practice to ensure the image is acquired and processed correctly to avoid poor quality, questionable images being used in press releases. 

Screen snaps, and other immediate captures, are not suitable for any subsequent comparative analysis or evidential use as they are not the original recording and the changes may not be known, repeatable or reproducible. 

The original data must also be acquired by someone with the competency of doing so. The owner of the video recording device may not understand what is the best evidence. 

It is important to remember that the integrity of the exhibit does not stop there. As the item can be easily changed in so many different ways, each change will result in a new exhibit. 

If a video is trimmed, it's not the original video anymore. It has had frames removed and it may even be a completely different recording type. The new exhibits integrity must link to the previous one and a new integrity chain will start for the new item. 

Trust in the exhibit can only come from understanding how it was created, and if it's been created from another exhibit, then what was changed in that process? 

Authenticity

Authenticity examines what is seen within the exhibit and if it is a true and accurate representation of that which it purports to be. 

To ensure authenticity, an exhibit may need processing, and therefore changing. Remember, if it's changed, then a new exhibit must be created to ensure integrity. 

Many videos may look squished and distorted. Many have the incorrect aspect ratio or have visible defects caused by their recording type. Many have lens distortion with straight edges being curved, and perhaps some have problems with their frame rate or video speed. 

Without analysis and the correct processing, these videos do not display an authentic view of the scene: they are not a “true and accurate representation” of what happened 

The most common however is date and time. Displaying an incorrect date and time can cause huge problems to an investigation and these should be correctly adjusted before being presented as authentic evidence. 

Validity

Every procedure used in the handling and processing must be valid. If not, why was it used and has it affected either the integrity or authenticity of the image or video?  

The easiest way to ensure validity is to follow a scientific model. 

For processing, restoration and enhancement we follow the Image Generation Model. The video or image is analyzed and the model is used to correct and present the visual data. Even resizing an image must use an accurate, repeatable and reproducible method. The process should be explainable, when needed, and free as much as possible from external bias. That is why processing using any Artificial Intelligence (AI) is generally not acceptable for most evidentiary applications.

The producing witness must ensure the evidence can be trusted. If they are unable to explain a processing stage because this has been conducted using an unexplainable computer algorithm, then how can the result be trusted in a courtroom? 

Comparative analysis, or offering a statement of fact to an object or item within the visual image, must also follow a workflow, with analysts using the ACE-VR standard for a science-based methodology. Analyze, Compare, Evaluate, Verify, Report.   

The creator and CEO of Amped Software, Martino Jerian, identified the need to protect officers and staff when dealing with images and video, and therefore ensure the credibility of the evidence, way back in 2008. Video units were doing all sorts to their visual evidence, using multiple pieces of software, and even private forensic service providers had a free range to use art instead of science in the analysis and presentation of evidence. 

As technology has increased, it has become easier to question the visual evidence and accreditation does go some way to ensure the integrity of the exhibit. Most CCTV units and forensic video teams are working towards ISO accreditation, and when I am asked how Amped FIVE can help them, I always start with the three points discussed above. 

With the science of restoration and enhancement as its backbone, FIVE has grown over the last few years to include copy verification, proprietary video decoding including audio and date and time extraction, metadata and frame data analysis and interpretation, advanced restoration and enhancement filters, multi-camera and timeline creation, speed, height and object measurement, annotation, and finally the creation of new visual exhibits with full forensic reporting. There are even editable assistant scripts that can be adjusted to fit your units Standard Operating Procedures (SOPs). 

Its purpose is to ensure the integrity of the evidence, the integrity of what has been done, the authenticity of the visual image, and the validity of every process completed. In short, it allows the technician or analyst to get a result and a judge or jury to trust what they are seeing. It should go without saying that the competency of the producing witness is a key issue but I think that discussion is best to be left for another time.    

When you next have video or images in your evidence, ask yourself, does it have integrity, is it authentic and are the methods used in its processing valid? 

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