It's almost amusing sometimes to hear younger investigators complain regarding how to solve a case without it being on video or having scientific proof. Have no fear, old fashioned police investigative techniques still work.
However, there are so many issues around forensics that some of the aspects might provide an interesting angle for a story. This Ars Technica article makes some good points about who is an expert, the scope of their expertise, how to educate the jury and most important - how to educate the judge. And then there's always the problem of the science not helping the case for the one who hired the expert, or when two experts who disagree.
Generally speaking, in federal court an expert witness submits a curriculum vitae to the court and the judge will make the determination to accept the person as an expert before they are allowed to testify. It's a great way to introduce opinions to support the facts into a criminal trial. Experts can also clarify why certain things happen the way they do, for example in a crime scene, that an average person/juror wouldn't be able to interpret on their own.
If you're curious about real life forensic experts, Dr. Henry Lee taught one of my advanced investigative classes and is well respected. He's also written several books about famous cases he's been involved in -- and still uses science to help reveal truth in criminal investigations.
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