Who is Carla Ruiz from Rules of Prey and what is their importance?

Carla Ruiz is a female artist in the Twic Cities. She would have been maddog's fifth victim and the third in the Twin Cities area, but she successfully fought him off and he fled. Carla later became romantically involved with Davenport and appears in interviews with him. When the maddog returns to kill her, he is killed by Davenport.