I just listened to a Dr. Drew show on which the guest suggested that what happens in these sorts of situations is the person actually does kill themselves but that they do so because of very credible threats that one by one their children, spouse, sister, mother, etc. will be killed unless they kill themselves.
There was a suggestion that there was an issue of domestic violence in her life? They need to do an autopsy and release the coroner results. (And any letter she might have left.)