One is defending their position by giving an additional explanation as to how the opinion was reached. This adds to the person’s creditability. By saying this is the most reliable opinion based on the available data, one is saying that all available data has been analyzed and evaluated. It also is stating that you are willing to consider data that was not available at the time your opinion was reached that has subsequently become available. This enhances the person’s credibility to the judge or jury and that they first consider all the data that was available. This will include data that may not be favorable to their opinion. In addition, it shows a willingness evaluate any new data that is made available.

You answered my question as to the methodology found at 921. Most think they need to say they followed step-by-step as it appears in the document. This is not correct. They need to be able to say what steps were followed and how they followed those steps. Then explain how this is equal to or better than what is found in 921. Quite often I do not use the two first steps mention in 921 when I am explaining it to the jury or judge. I think a lot of investigators were testifying get hung up on the number of steps in 921 and failed to just explain what they did and how that works as an acceptable methodology.

One more to say most likely correct or true then it is given the impression that there may be other conclusions that are also correct or true. If you’re going to do this, you need to prepare to explain why your conclusion ranks above any of the others.

Jim Mazerat
Forensic Investigations Group