Could be Ptarmigan is really a 70+ year old lady...
This is bull crap, a 70 year old who had lived for decades in a neighborhood is said to be out vandalising cars.
WTF, she has never shown any propensity to harm a neighbor in the past.
More is going on here then we know, perhaps she saw a drug deal going down and some one has to frame her so she forgets what she saw. ? Keep the police engaged on this and she totally confused as would be someone half her age be.
70 today is not that old, nor does it lead most people to outrageous acts. I believe everyone involved in these acts of vandalism should be checked out as she may be have been set up by people that know she saw something and want to insure nothing she says is believed.