To follow your example, consider a circumstantial evidence based case against a mother who murdered her child. Absent direct evidence, the prosecution has to address the issue of motive, and in doing so they might look into the mother's journal to show she felt burdened by motherhood, was jealous of relationship between the child and the father, or perhaps some other motive. Of course many mothers have such feelings and vast majority who do never harm their children, or at least come no where close to murdering them.
However, when a mother does murder her child and there's no direct evidence to prove as much, the issue of motive must considered along with the circumstantial evidence to find a person guilty beyond any reasonable doubt. Such is necessary because if there is no conceivable motive and rather the mother's journal was full of talk about how much she loved her child, the defense would show that evidence and call her along with others as character witnesses to corroborate as much on the stand, and that evidence suggesting innocence would leave reason to doubt the circumstantial evidence based case against her.
As for this case, there isn't evidence of any ritual, not in Misskelley's many confessions or otherwise, and Fogleman addressed that in his
closing arguments at the Baldwin/Echols trial when he explained "whether it was a sacrifice or ritualistic sacrifice or simply those beliefs motivating this defendant, don't matter." In other words, motive need to be manifest overtly like with the craft to blood you suggest for it to be understood within the context of evidence which connects Echols to the murders, both that which was presented at trial and otherwise.
Furthermore, the issue of motive likely would've never came up had Misskelley testified at the Echols/Baldwin trial, as that direct evidence along with the circumstantial evidence would've made addressing the issue of motive superfluous. However, Misskelley changed his mind about testifying shortly before the trial started, making the one recorded confession the prosecution had from him at the time inadmissible, and hence leaving them to work with what evidence they were allowed to present in court.
Anyway, I hope that might help you better understand the reason I created this thread, and that I mean no offense to anyone who has/had interest in the occult. I'm of the opinion that people have the right to believe whatever they like, and it's only when one infringes on the rights of others that their motivations for doing so become an issue. Beyond that, the occasional occultist murderer doesn't impugn upon occultism any more than for example an occasional vegan letter bomber impugn upon veganism, which is to say not at all. People come up with all sorts of reasons to do all sorts of horrible things, but it's not the reasons which are at fault, it's the people who infringe upon the rights of others by acting on them.