While there's no question in my mind that Jerry is a "perilous psycho" in the uncanny mode, I had to think whether or not STEPFATHER also made use of the uncanny version of the "bizarre crime." Certainly Jerry's not an artful psycho: he clubs one victim to death with a board. But I finally decided that his motif of moving from family to family in pursuit of his twisted ideal qualified as a bizarre crime in itself-- though of course, like any uncanny facet of a narrative, it can be reconfigured to take on a purely naturalistic phenomenality, as one indeed sees in some of STEPFATHER's imitators.
I don't think that PRAYING MANTIS was an intentional copy of STEPFATHER, foi the later movie just doesn't seem to "quote" the earlier one the way a true knock-off emulates its original. It's interesting, though, that the movie to which MANTIS has been most often compared (on IMDB) is also from the year 1987: the Theresa Russell vehicle BLACK WIDOW. In any case, here are the similarities and differences:
(1) Both narratives deal with a psycho who repeatedly moves from family to family, killing as he or she goes. However, Jerry Blake kills all the members of the family into which he marries, while Linda Crandell kills only the man whom she marries.
(2) In both films, the cops assigned to the case assert that the unknown killer must have a major trauma in his or her background. In both films, the trauma is never revealed to the audience.
(3) Both psychos are artless killers who display no more particular creativity in their methods of murder. Blake uses blunt objects or edged weapons, while Crandell uses poison.
(4) In both films, young members of the family into which the psycho marries are largely responsible for exposing each evildoer, though the initial person to suspect Crandell is the sister-in-law of the first wife of Crandell's intended victim.
(5) In my critical opinion, neither film does much of anything with the psychological potential of their scenarios.
Given that I've stated that there's no single element about the uncanny film that couldn't have appeared in a naturalistic film, it behooves me to ask then: what makes Jerry Blake an uncanny psycho, while Crandell's only naturalistic? I've alluded to at least part of the answer in saying that the "twisted ideal" Blake pursues gives his "bizarre crime" the tonality of the uncanny. In contrast, Crandell really doesn't have an ideal as such: she's merely compensating for her past trauma by trying to find someone who won't betray her, possibly in the form of a father-substitute. This would also accord with what I've written about the nature of all naturalistic fictions: that they must always seem to be "logical extrapolations from [the author's] observations of experience."
Since the physical phenomena in STEPFATHER and in MANTIS are essentially identical, the only thing that can possibly separate them is that the former is far more invested in the tropes of story-telling-- that is, in the principle of artifice-- as opposed to that of experience, a.k.a. verisimilitude.
"Affective freedom," rather, stems from the author's intention to privilege the tropes from the domain of literary artifice over tropes that signify adherence to worldly verisimilitude...-- ARCHETYPE AND ARTIFICE PT. 4.
But once again, I stress that I can only make such a judgment by imaging a *threshold* that separates the limitations of "affective freedom" in a naturalistic work from its more intense expression in an uncanny one. It's a subjective judgment that STEPFATHER just barely manages to step over that threshold, despite all of its similarities to PRAYING MANTIS; that STEPFATHER is more a figure of uncanny artifice akin to the much more outrageous-looking Jason Voorhees (in his early incarnation, that is). But I still favor this approach over a "recipe" mentality, in which, say, the presence of any psycho of any kind automatically crossed into the greater category of the metaphenomenal.