Patti Sue Diamond is the main villainess from "Ballad for a Blue Lady," episode 7.09 of Murder, She Wrote.
She was played by the late Florence Henderson.
Patti Sue Diamond is a blues singer and the wife of country star Bobby Diamond, as well as an old friend of Jessica Fletcher. However, Patti Sue learned that Bobby had found a younger woman and was planning to leave her, as she had found a two-page note written by Bobby where he stated those exact sentiments.
Enraged, Patti Sue planned to kill Bobby, and knowing her husband's habits, the vengeful villainess laced a bottle of Bobby's favorite bourbon with strychnine and placed it in the farmhouse. As Patti Sue expected, Bobby drank the poisoned bourbon and succumbed to the effects, and to make sure she had a good alibi, she called his hotel room at 10:30 after her performance, making sure he had his routinely drink. An hour later, Patti Sue stopped at the farmhouse and saw her husband lying dead. She later set up the murder to look like a suicide, placing the bottle of strychnine next to the bottle of bourbon, and leaving the second page of the note behind to make it appear that Bobby had written a suicide note.
Patti Sue's reveal ironically came when her villainous stepdaughter attempted to kill her by poisoning her coffee, as it was her attempt to make it look like Patti Sue killed Bobby and then killed herself that led to that being true. Patti Sue survived the poisoning attempt due to having eaten a big bowl of ice cream, which lined her stomach, but after Jessica deduced Patti Sue's role in Bobby's death, Patti Sue confessed to the murder. After her confession, Patti Sue was arrested (off-screen).