Two heads are better than one

Well, you can imagine what my weeks been like after my ‘announcement’, surrounding my resignation from the Police Service. Luckily it’s been very positive. Just keep your fingers crossed that the positivity ends up paying the bills!

My inbox has also had a number of international ‘peer reviews’. Most people identify a peer review as a method to identify the validity of a result, conclusion or opinion. It is a trusted method to ensure that an expert’s work is agreed by that scientific community and can therefore be relied upon.

It is common for peer review to occur at the end of an investigation. Perhaps after a clothing comparison has been completed or a technical clarification of poor video has been processed.

My point here, is to highlight the importance of conducting a peer review much earlier on as well, not just at the end.

Acquiring, interrogating and processing surveillance video is a minefield of challenges. If those challenges are not met with a competent workflow, all other work, such as the clothing comparison example, could be called into question and negated. Cases where no further analysis is required after processing are actually more common. It is imperative therefore to validate the process being used if there is no intention to validate any opinion or analysis further on.

It is very easy to carry on down a specific pathway without pausing to confirm you’re going the right way. The technical opportunities afforded to any person with a standard computer have now reached a level where video and image manipulation is relatively simple. As a result, the needs of the administration of justice may be met, but at the cost of any forensic methodology and integrity.

How many times have I asked a colleague to look over my calculations regarding frame timings or measurements?  Whether they are sat in the desk next to me or in another time-zone, it’s too many times to recall. These are both forms of investigative peer review. I didn’t want to carry on until my work had been validated.

It is vital that the pause button is pressed early on, during the initial interrogation of digital surveillance footage.

My process flow can be detailed as:

  1. Interrogate Interface
  2. Interrogate Data
  3. Test Theories
  4. Identify Workflow
  5. Process
  6. Validate
  7. Report

The initial interface and data interrogation is a fundamental procedure that enables you to identify your start point. If you don’t understand what you have, how can you proceed?

In most forensic disciplines this start point is of a known factor. In traditional forensics, it could be a hair or a fingerprint. In digital forensics, it could be a FAT32 partitioned HDD.

In digital multimedia forensics, where the majority of the product comes from surveillance recording devices, it may take a little time to identify the start point and then the relevant information that will affect your forensic workflow.

It’s at the ‘Validate’ process where Peer Review comes in. I may decide not to ask for a Peer Review. I may validate against other software or processes. I may be very comfortable with the format being examined, having dealt with it many times.

However, there are many times where I am investigating a new format, in a new interface. I may be conducting a new and progressive technique to identify missing frames, incorrect scaling, or faulty colour representation.

It’s at these times where two heads are better than one.

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By Spreadys Posted in EEPIP

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