Though The Telltale Heart does remain a favorite in American literature, I'd like to think we still probably owe our greatest debt to the phenomenon with Shakespeare's character Lady Macbeth and her somnambulistic drama and hand-washing scene. She has interpreted in a variety of ways (depending on the tenor of the times regarding females), from a cold, calculating and aging opportunist who is, on some level, eventually unable to reconcile her greed and ambition with the deeds she has both encouraged and participated in, to Roman Polanski's version of the 60's in which she seems more like the naive young wife of a corporate raider who simply does not consider the long term psychic consequences of having to provide the pragmatic follow through in the inevitable aftermath of her husband's hubristic ambition. However, even the doctor Macbeth arranges to treat his wife admits he is unable to successfully in that she is not truly sick but "troubled with thick coming fancies" of memories she has of past dire deeds. When asked to cure her, the doctor tells Macbeth he cannot and "therein the patient/must administer to himself". It's probably one of the earliest examples of guilt on the psyche, even if all his works on the futulity of cheating or avoiding guilt borrow heavily from even earlier classics, like Oedipus, Perseus, Agamemnon, etc..
It strikes me that this is a thread in which we cannot help but use this as a lens to see the world through our own vision and experience. For one thing, none of us know exactly what kind of mental state or professional diagnosis one could pronounce on KC although we all certainly have our favorites. Even the professionals tend to disagree about what medical diagnosis may be accurate or appropriate (and I'm sure there will be lively debate on that at trial if it becomes a salient strategem). To complicate matters, there is even further academic debate amongst professionals as to the presentation, treatment, extent, etc. within a single consensus of ailment or condition. And I'm sure that, there is even room for variables about the reactions of more than one sociopath (should that be the agreed upon term) to the same or similar set of circumstances. Certainly PTSD is a mystery in that some people suffer from it terribly and in a debilitating way and others are able to cope or heal even when they are both subjected to the same traumatic impetus.
What mucks this up even further for us is that we are not dealing with a subject in vitro, but someone who is part of a strange and dysfunctional emotional ecosystem of a family. Someone who is being tried for a crime and who is very secretive, subjective and dishonest about her behavior - as are most of the people who are close enough to her to give any kind of useful anecdotal reports to help us form our opinions.
And then our own interpretation of any given behavior varies so widely it has taken hours of contemplation and rumination. Just the jailhouse reaction as an example. Her reaction can plausibly fit any number of interpretations, from guilt to surprise to lack of affect to faked affect, ad infinitum ad nauseum.
I find all of our interpretations thoughtful, revealing and interesting (and suspect they may also change with our own perspectives and moods), more about ourselves and our own frames of reference perhaps. However, even if we are likely to capture a genuine glimpse of an actual "anniversary event", how that may or may not play out in the trial - which will be conducted by attorneys who have a very strict interpretation of what is either admissable or germaine, is still very much up for grabs and is likely to be vigorously debated by both sides.
One thing seems to be certain, if unfortunate. Regardless of how we would like to vicariously observe her behavior and use it to help us justify or understand what we believe she is going through (or not) mentally, it is very unlikely to have any impact on this trial other than during a penalty phase and that is in the hands of the attorneys who can manage to persuade the jury that her behavior - if it indeed comes down to an "anniversary reaction" this is part and parcel of should be interpreted sympathtetically or not.
I think the prosecution will have no trouble reaching the criteria for sanity at the time of the crime from the fact that her behavior both before and afterward (however erratic) is organized and calculated enough to show she is capable of elaborate, premeditated cover up. If somehow the defense can cast her prior or subsquent behavior in a light designed to elicit sympathy (PPD, mitigating emotional circumstances) it may, at best, be a vehicle for getting the DP off the table, but I seriously doubt it will do anything to exonerate her and have her walk out of any courtroom an innocent or free woman.