Each crime has multiple facets of forensic science to explore and every crime is different. Some might have a particular aspects of DNA, blood splatter or ballistics analysis. Another may involve river flow, climate and decomposition factors. Another might require multiple fibre analysis from clothing right through to laser scanning. Each crime scene detail is different, each forensic analysis meticulous, every discovery an important piece of the puzzle the presenter is completing.
When we hit difficult science concepts, we briefly leave the investigation timeline and go to a short science breakout. Here the presenter meets with the relevant scientist and re-enacts the actual tests on the evidence, illustrates the process, sometimes becoming a human-guinea pig himself to demonstrate and translate the science into easy to understand bites for the audience.
This way when we re-enter the timeline of the investigation, the viewer is armed with scientific knowledge that applies to this specific case.
And when all the pieces of the puzzle are finally put together, it will be the most satisfying conclusion… as the knife clatters to the floor, or the gun sits smoking… as we already know how the science proved the truth and solved the crime.