Terrifying Teacher

In Book 4 of the MURDER IN MARIN Mysteries:
News that elderly Henrietta Hammer has died, Sausalito's retired fifth grade teacher, who once terrified her students including Sheriff's Detective Eddie Austin, newspaper publisher Rob Timmons and his assistant Holly Cross, is greeted with bemused nostalgia.
But Hammer, who was left a very wealthy widow by her enterprising late husband, was the target of every one of the town's charitable societies none of which could afford to await her natural death.
It all appeared to be a perfect plan until the secret Mrs. Hammer kept for half a century inconveniently appears.