I find it a bit disturbing how often this comes up on this forum, but I am an investigative agent for a large state agency. I do not work in Virginia, although my work has taken me to Virginia many times. My specialization is sex crimes. In a past life I was a parole officer, also not in Virginia, but my specialization there was also with sex offenders. I supervised many sex offenders who were convicted in Virginian courts. Virginia has relatively strict supervision terms but a very low interstate transfer fee, and they greatly neglect their out of state offenders, so many, many Virginians who are under supervision transfer out of state if they are able. I have actually been to the jail where it is likely Chris will be detained if charges are brought. I have testified in Virginian courts in sex offense cases.
My perspective on Chris as an offender, if his claims are true, are that he is almost certainly an opportunistic offender. That cuts both ways. He (possibly) fucked his mother. He (possibly) did this because of his proximity to her, his constant contact with her, and her inability to resist effectively. Chris is mentally unwell (this may be the understatement of the century). Ever wonder why so many grandpas fuck their grandkids and end up on the registry? Its unfettered access and sexual frustration. The upshot of this is that he isn't likely to ever be a threat to the general public, in that he won't grab a kid off a playground and haul them off. The downside of this is that literally anyone or anything in Barb's position was also fair game- someone so sexually stunted but with such a focus on sexuality as Chris could have easily fucked a child, a mentally incapable person, or even just an animal. An ability or inclination to resist would likely reduce the odds of such a thing to near zero, but some kids or mentally infirm do not have that ability or inclination, and opportunistic offenders will use bribery or shame their prospective victims.
Now, how will the following events go?
For one, some of this hinges on what comes of Barb's medical evaluation. We may find that Chris is simply saying crazy shit. He may have never sexually abused her, or done so in a manner that would not be consistent with injuries, abrasions, or a sample being left behind. If this is found to be the case, it makes prosecution much more difficult if they even attempt to pursue it.
Absent the possible sexual abuse, the conditions Chris lives in with Barb will not rise to the level of elder abuse. Although filthy and verging on being a hoarder, their environment is nothing compared to many others out there, and as crazy as Chris is, there is much worse out there- perhaps not so many as entertaining, but there is a lot worse.
How will the interview with Chris go? Well, depending on the findings of the examination, there may not be one. Being known as crazy- and there is an overwhelming body of evidence that although he likely will be held as mentally capable he is certainly prone to saying untruths- there is a strong defense to any claims made in an interview, even if Chris declines to have a lawyer present. Interviewing the mentally ill is often fruitless. I've had random nutjobs with naught but trespassing and vagrancy offenses claim to have killed people on vivid detail, and I've had unrepentant serial child rapists tell me extremely detailed lies. Chris will receive pretrial mental health examinations, he will speak to a psychiatrist, and his attorney and pretrial services will attempt to enroll him in mental health care if he is allowed pretrial release (which he probably will be).
As a general rule, Virginia is strict in sentencing but tends to suspend much of the sentence if not the entirety if the offender is not a recidivist. Much to my irritation, I have charged and successfully had many felons convicted with new offenses up to and including armed robbery only to see their Virginian cases of supervision partially revoked or not even be retaken by Virginia (which is illegal under the interstate compact agreement but Virginia does it anyway)
Chris does not have a major record and his past offenses are far enough distant, and of a substantially different nature, that they are not likely to have him remanded or have him receive active time. Chris's documented absurd behavior and internet antics, coupled with him coming out to admit everything, provide the defense with excellent material to argue mitigating circumstances, and if no physical evidence is found perhaps even dismissal with a new social worker checking up on him regularly. But we really need a few more pieces of this puzzle to get a great idea of where we're going.
Depending on Barb's state of mind, she may be going to a group home. I don't think we really have a great idea of where she is at mentally nowadays or how incapacitated she is.