Symptoms include extreme views and shifting feelings. For instance, they might think in terms of “all good” or “all bad.” Likewise, they might think of someone as a friend one day and then an enemy on the next.
A serial killer diagnosed with a borderline personality disorder is Jeffrey Dahmer. He took the lives of 17 men in more than a decade.
We cannot talk about the mental illnesses that serial killers have without mentioning schizophrenia, a condition where the person interprets reality differently.
Schizophrenia involves distorted thinking, perception, sense of self, behavior, and emotions. Patients with schizophrenia may have delusions and hallucinations where they see or hear things that aren’t there. These hallucinations and delusions could drive them to hurt or even take lives.
David Berkowitz, also known as the “Son of Sam,” killed six people and claimed that his neighbor’s dog, Sam, made him do it. Experts diagnosed him with paranoid schizophrenia.