Detective Sparks' father was a beat cop that was shot down when he was thirty-four. She wanted to make sure he didn't die in vain. She wanted his death to mean something. She decided to dedicate herself to the police force and follow in his footsteps. She quickly moved her way up the ranks through dedication and hard work and soon became a Detective.
She was one of the main investigators for one of Grendel's first hits, showing off her analytical acumen, figuring out the details of the crime scene in a way that the other cops couldn't. It was clear to her that the unknown killer was a long-term threat to the city.
The mayor eventually makes her the head of a secret task force to catch Grendel, who controls all the crime in the city and has completely eluded their attempts to catch him. However, despite her hard work, she can't get anything on him. Her secret boyfriend, Lucas Ottoman, is a reporter who is also obsessed with Grendel, but he isn't having any luck either.
However, after she gets back from working one of his crime scenes, she finds Lucas shaking in bed. He saw the whole thing and was horrified at seeing Argent, the police force's answer to Grendel, slaughter numerous criminals in cold blood. He thinks the police are as bad as Grendel for using Argent, but she argues back that they need to fight fire with fire. They start to have some distance in their relationship over this issue.
Liz interrogates the only survivor of Argent's slaughter, but Grendel slips some glass in his food and he dies. She is getting nowhere, but unbeknownst to her, Lucas has figured out Grendel's secret identity: Hunter Rose. But he needs more proof, so he doesn't tell her. She can tell he's holding out on her, and she gets more and more annoyed with him. She even finds some surveillance equipment in his apartment, but he won't tell her anything. He wants to be sure before he says anything, this is too dangerous an issue.
She starts trying to get information from the other mob bosses, but even they feel bad for her, having to go up against Grendel. She and Lucas finally reconcile.
Lucas finally gets the final information he needs and is ready to go to the police, but Grendel knows that he knows, and kills him. Liz breaks into the apartment just as Grendel is setting it ablaze. She shoots at him but he deflects the bullet back at her, and she loses an eye. She tries to save Lucas' corpse, but is burned very badly all over her body. She bitterly has to retire to live her life in pain.