Liza Warner witnessed her two roommates being murdered by the "Killer-in-Boots". Disturbed and ashamed by the incident she found encouragement from the female officer who said she had the attention to detail and bravery of a police officer. Those words combined with her restless nights motivated her to enroll in the Police Academy to find the killer of her roommates.
At her graduation a washed up recruit decided to toss a hand grenade in the group of graduates. It was only by the intervention of Warner knocking down the recruit and tossing the grenade into a trash can that everyone's lives were spared. Warner worked as a beat cop after that and stopped many more criminals who prayed on the innocent.
Marc Guggenheim stated in an interview Lady Cop will be appearing on Arrow sometime this year. She will be called Liza Warner on the show. She is portrayed by Rutina Wesley (2015).