I think that is a great, hard hitting summary of the personality traits that the perpetrator could have. I also like the part about mellowing with age, but still retaining the core personality. Then something brings it to the surface again.
Though the area is growing and has seen a certain number of transplants, it still has alot of "from here" long term residents. Maybe the police could interview retired principals / teachers with that profile in mind? I wonder what class reunions are scheduled. Likewise, retired police might remember a local young woman with those traits from a minor arrest.
I also think it could be beneficial to combine the personality traits with the perpetrator's walk. She does not walk or move like a former athlete. Rather, she seems clumsy and possibly slightly "pigeon toed".
So, maybe combine those traits with possible physical traits and you get a profile of type A personality girl with a confrontational streak and who was also not part of the "athlete / cheer leader" crowd- and maybe had an innate dislike of girls from this group? Years later, a "cool female athlete" type sets her off... .