Liann (Julianne Chidi Hill) is a villainess from "Crash Course," the second-ever episode of The Rookie (airdate October 23, 2018). She is a meth addict who was confronted by Officers John Nolan and Talia Bishop, who reported to a scene where a car was set on fire.
Liann confessed to setting fire to the car, which belonged to her meth dealer, Fun Gus. She stated that Gus stiffed her on the product, claiming that she paid for $20 worth of meth but only got half of that amount. Liann also added that she was looking for Gus, while revealing that she stabbed his brother during her search. Nolan and Bishop handcuffed and arrested Liann, with the former discovering that the knife she had was coated with blood that was relatively fresh.
The villainess led the officers to the direction of her dealer's brother, only to find him in an alley. Nolan's check for a pulse revealed that the victim was dead, revealing that Liann actually killed him. Despite this, the evil Liann claimed that she, not her dealer's brother, was the actual victim, and it was later in the episode that Liann officially booked for (among other things) murder.