Kate's mother

Background
Kate's mother lived a life of mental illness. When Kate was five years old, Kate's mother committed s*icide by leaning over the railing of a bridge. In her obituary Ken wrote that her death was related to illness because he didn't want people to know she had committed s*icide. Her death has since affected both Ken and Kate.

Trivia

 * She is the only character in the show with a given death date and a cause of death