Cindy,How sad that no one saw what had to be obvious signs of depression so that this tragic end could have been prevented. I feel so sorry for her family.
Manic-Depressives can change states going from mania to normal to depressed in a little over 48 hours. You never know what will set them off, their feelings are generally easier to hurt than a normal person, they can be super sensitive. Parents, siblings and friends cannot readily read their intentions and predict their actions.
Seeing and doing something are two largely unrelated items, you cannot guard a mature adult person 24 hours a day, particularly one who has a full time job and travels independently.