This woman seems to hold high moral standards, but I must confront the allegations of the store owner. I am not well read on kleptomania, but it certainly seems that this is a probability. However, other possibilities should be considered. It is interesting that you describe this individual as a strong codependent, since psychodynamic interpretations of kleptomania have noted that it may serve as a defense against intense dependency conflicts. Depression, and attempts to replace a loss, may also be associated with kleptomania.
Narcissistic injury is reported to precede kleptomaniac acts in some cases.
The possibility of a complex partial seizure disorder cannot be excluded, from what you have said, though my guess is that this won't pan out. Still, if this woman is in her 60s and these problems are of recent onset, I would want to rule out a frontal lobe tumor or other organic causes of a change in personality. I would consider a psychiatric consultation to see if an SSRI, such as Prozac or Zoloft might be helpful, as these agents are useful in both OCD-spectrum and depressive disorders.