True crime horror stories can make society more aware of the potential for evil. They can lead to increased safety measures, like better security in neighborhoods. For example, after a serial killer strikes, people might be more cautious about walking alone at night.
Another disturbing story is that of Jeffrey Dahmer. He not only murdered his victims but also engaged in necrophilia and cannibalism. He would target young men, often from marginalized communities. His actions were so sickening that it's hard to even fathom the kind of depravity that led him to commit such crimes.
In many cases, crimes depicted in various forms of media might have elements drawn from real-life incidents, but they could also be heavily fictionalized for entertainment or narrative purposes. So, it varies.
In many cases, true crime stories are based on real events and facts. But sometimes, there might be some dramatization or artistic liberties taken for the sake of storytelling.