In a strange twist, the Aurora shooter mailed a psychiatrist detailed plans of the shooting. The tragedy might could have been avoided with this information except the package was left sitting in the mailroom unopened until after the shooting happened.
Just for the record, physician/patient confidentiality would not have applied to this situation. The doctor would have had a duty to warn in this instance under something known as the Tarasoff Doctrine.
"The world is a mess and I just need to rule it." --Dr. Horrible.