Mare's ex-husband Frank Sheehan was out celebrating his engagement on the night of the murder. As Erin's best friend Jess seems to believe him to be DJ's biological father, his character is called into question. While he admits to having an acquaintance with Erin, who was her student in high school, his DNA results clear him from being DJ's father. It potentially lets him off the hook without any further knowledge of his involvement that could translate into a sturdy motive to go through with the murder.