Maybe Mrs. DiLaurentis was the “fragile patient” at Radley who pushed Mrs. Cavanaugh out the window. She had a stint in Radley and was grateful for their work with her so she joined the board. Mr. Hastings knows this. He had to have known. Especially if they had an affair that produced Jason. They work have been extra involved in each other’s lives. Maybe Mr. Hastings helped cover the whole thing up because he didn’t want the mother of his son to go to jail.
Maybe mrs d is the one with the twin and her twin was in radley. Now her twin is out and after spencer for killing her daughter, Sara Harvey.