"There are states of being that are neither warm, nor cold- neither positive, nor negative."I can't completely rule out the perp. being known to Missy or at least to someone in her circle, but I think the fact that seven years later the Police have not advanced the case any further makes me lean more towards the perp being a complete 'randomer'.
Ok, fake new age mysticism aside, I think there is a suspect possibility that is "in between" being part of the victim's circle and being random.
Such a potential perpetrator would have ties to an individual in the victim's circle and then act on behalf of that person.
The victim's uhmm...... "extracurricular activities" could lead to a situation where a perpetrator concludes that the victim's activities present a threat to the marriage of a friend or relative. They then move to protect that marriage by, well, murder.
In this possibility, the perpetrator could be a protective sibling or close friend. If the individual also has a failed marriage of their own stemming from similar activities, resentment towards the victim might increase further.
Such a possible perpetrator could be actively religious. But.... one can also be very secular and still development a protective sense of "N0- not going to let this happen to somebody else." and have a deep social, but not religious, opposition to people engaged in certain activities.
Anectdotaly, I once had a non religious neighbor (and non murderous) in extremely secular SOCAL who had been "burned" once in a marriage and had developed an open dislike of women she deemed to be "players" in regards to married men.