The Mysterious Charlie Chop-off
False confessions can and do occur among the mentally ill. In Interrogations and Disputed Confessions, Dr. Gregory DeClue, an expert on forensic clinical evaluations, discusses the interplay between voluntary confessions and mental illness. A solid confession must be a product of an unconstrained and freely-offered choice, made by someone with full awareness and appreciation of what he did. If Soto, who had schizophrenia and substance abuse problems, had experienced symptoms before, during or after the interrogation, he probably would not have offered reliable information, especially if suggestive or coercive interrogation techniques were used. Whatever a person says under such circumstances should have corroboration from other evidentiary sources.
It's often the case, DeClue says, that interrogators identify psychological vulnerabilities through which they can extract a confession, and it's not difficult to persuade someone who already has a tenuous grasp of reality to accept the interrogator's version of the truth. In fact, in Gelb's book, one of the detectives she follows tells her, "The goal is to get the confession. What bothers me is thinking back to what I might have done, at times, just to get the confession. I might have done — possibly anything." The detectives profiled by her certainly don't refrain from browbeating mentally defective subjects and they apparently feel satisfied as long as the person tells them what they want to hear.
While reports indicate that Soto readily confessed, offering a delusional motive about God's command, we don't actually know what happened behind closed doors before he said anything. We're not informed about his IQ, level of anxiety, possibility of substance abuse at the time of the arrest, or his prior awareness of the facts, all of which can prompt a false confession—especially if he internalized the events before the police apprehended him. In addition, we have no idea if the interrogating officers used crime scene photos, threats, or other types of persuasion to get a confession. Without this information, it's impossible to determine how credible his admission actually was. A psychotic individual can in fact believe that he has done something when he has not, especially if told he has done it.
Yet it's also true that some serial killers have killed repeatedly while psychotic or under the influence of substances. Herbert Mullin, a long-time drug user in Santa Cruz, acquired the bizarre notion during the early 1970s that he had to kill "sacrifices" to prevent a natural catastrophe in California. Not far away in 1978, the "Vampire of Sacramento," Richard Trenton Chase, murdered a man to try out a gun, then killed a woman to drink her blood and slaughtered a family to grab the baby for its organs. He believed his blood was turning to powder and he needed to replenish it. As well, during the 1980s, Harrison "Marty" Graham actually resided with several corpses in a building in Philadelphia. He claimed they were there when he moved in, but it turned out that during sex, he sometimes killed the woman he was with and then just left her body in the apartment to decompose. He pleaded not guilty in virtue of his mental illness and one expert insisted he was not even competent to stand trial, but he was nevertheless convicted. In fact, all of the above-named individuals were convicted of murder. A person can be psychotic and nevertheless sane, i.e., aware that what he is doing is wrong.
Whether Soto confessed from within a deluded state of mind or was aware of what he had done despite his illness, in the end his mental instability did become an issue. It's not always about just getting a confession.