reporter: in the back of the police car, 22-year-old petito tearfully claims she is the one who initiated the fight. after a few quick questions about her injuries. kind of looks like something hit you in the face. i don t know. over on your arm, shoulder, that s new, that s kind of a new mark. i don t know. reporter: the officers turned their focus on pe tito s action instead. were you attempting to cause him physical pain or physical impairment? what was the reason behind the slapping and stuff? i was trying to get him to stop telling me to calm down. reporter: for nearly an hour, police questioned the couple about their relationship separately, and determined laundrie is the victim. so at this point, you re the victim of a domestic assault. reporter: it is something even laundrie finds surprising. i love her. it s just a little squabble.