There was a woman back then who chose to poison her husband’s Tylenol and, who I believe was the actual Tylenol murderer. She bought new bottles of the capsule Tylenol, and placed poison in several, which she gave to her husband, eventually killing him. To cover her tracks, she bought another bottle or two, poisoned one or two pills in both, then secretly returned then to the drugstore shelves at other stores. There were no safety caps or seals like today and after her actions, they were required. Two random victims fell ill and one, I think, died.
She, if I remember right, tried to sue Tylenol makers for killing her husband when his insurance did not release his funds because the investigation had not determined yet if his death was accidental or murder. That drew too much attention to her and eventually, she was caught and convicted.
It was on one of those TV reality shows like Forensic Files some time back, because they went into great detail about tracking down the poison used and where she could have gotten it.