I've only read one true crime story. Helter Skelter, by Vincent Bugliosi and Curt Gentry.
I read it while in college and it gave me lifelong insights into the legal system.
Bugliosi was the lead prosecutor against Charles Manson. He recounts the police investigation, how the old-time cops didn't think they needed to preserve evidence and bungled a lot of it.
After years of watching CSI and NCIS the general public has a pretty good idea of the importance of gathering all the evidence they can find and basing their findings off of what they have.
Back in this time scientific evidence was in its infancy. Silly since it had been in novel form since Edgar Allen Poe's Murders in the Rue Morgue and all the Sherlock Holme books and movies.
What I learned from the book and has still stayed with me fifty years since reading it was:
1. The importance of obtaining evidence, chain of possession, and keeping it safe.
2. Analysis of the evidence. They didn't have DNA at that time, but fingerprints and blood type gave clues. I remember that a boy found the gun and after watching a number of TV shows and movies knew not to touch the gun and picked it up with a stick. When he gave it to the police officer, he grabbed it with his hands on the barrel ruining anything they might have gotten from it. They knew the killers drove away from the Polanski home and which way they went. They knew they took off their clothes and threw them out of the car. They reenacted doing this and then found the clothes.
3. Reconstructing the crime scene by using the evidence.
4. Building a hypothesis of what happened.
5.Canvasing the area and interviewing all who knew them and who might have wanted to harm the victims. This led to the house the Polanski's lived in having been owned by Doris Day's son, and when she visited her son there saw Charles Manson and he gave her the creeps. Her son turned Manson down on recording Manson's music, giving him motive.
6. Jail house snitches. None of the evidence at the scene pointed directly to any of the Manson Family. The same with the Labianca's. It was the women of the family while in jail on other charges that broke the case open.
7. The most important part of prosecuting Manson was to psychoanalyze him. What was his motive. Without motive, no case. Once the case was handed over to Bugliosi he had to analyze the evidence and when it pointed to Manson then getting into Manson's head and understanding what and why he was always in prison and what happened when he got out. Stephen King's The Shawshank Redemption focuses on inmates becoming "institutionalized." Manson whenever he was released, committed an even worse federal crime so he would get right back in.
8. The importance in understanding the evidence and finding motive took psychology. That criminology and psychology go hand in hand in establishing proof for conviction.
9. The pitfalls of the trial. The different tactics the defense attorney used to try and get his clients acquitted.
10. While teaching both psychology and high school law this book and showing the documentary based on it opened up my students' eyes. It made me a better teacher.
I have never felt compelled to read or watch any true crime books or shows since. I'm content with fictional ones.