Kate was raised by her widowed father, Trevor Lockley, who is also a police officer, who taught her to put her emotions aside and to take care of herself at all costs. She first meets Angel while investigating a case undercover involving the brutal murders of several patrons of D'Oblique, a popular singles bar. She initially believes that it is Angel himself who is behind the killings, but changes her mind after he saves her life from the real killer (a parasitic demon who was possessing the bartender). Kate's subsequent encounters with Angel lead her to trust him as a helpful stranger, and she, in turn, assists him, using her position on the police force to provide him with information about some of his cases.
When she discovers that Angel is really a vampire, her black and white view of the world is shaken, and she delves into the darker side of Los Angeles. On one such investigation, Kate finds her father's lifeless body- completely drained of blood.
After her father's death, Kate struggles with her relationship with Angel; she undeniably has feelings for him, but blames him in part for failing to keep his fellow vampires away from her father (despite knowing about Angel needing to be invited into a dwelling by the resident), and subsequently becomes increasingly adversarial toward him, taking her newfound hatred of all vampires out on him. Obsessed with ridding the city of "his kind," Kate is the first to investigate any calls matching the "otherworldly" profile, even if it's out of her jurisdiction. She develops an intense dislike for Wolfram & Hart and the clients the law firm represents, but at the same time shows an equal resentment to Angel for exposing her to this world.
Her obsession with supernatural cases becomes her own undoing: after Angel attacks a cop who had brought back deceased police officers as zombies in an attempt to cut down on crime- unaware or unconcerned that the zombies use excessive force to deal with relatively minor crimes such as jaywalking-, she is eventually fired from the LAPD. In the aftermath, Kate calls Angel and blames him for ruining her life, then attempts suicide by washing down prescription pills with hard liquor. However, after he has his fabled epiphany, Angel goes to Kate's apartment, breaks down her door, and holds her under a cold shower, saving her life. When she comes to, she thanks him for doing so, but then harshly orders him to get out.
That evening, Kate and Angel come to a reckoning and she forgives him, believing there is a higher power at work and they're not alone in the never-ending battle against the forces of darkness. When Angel asks her why, she replies that she never invited him into her apartment.
She never appeared again on the series, possibly due to Elisabeth Röhm joining the cast of Law & Order. However, in one episode soon after her last appearance, Angel mentions to his friends that they no longer have a friend on the police force.
Kate reappears in the seventh issue of Angel: After the Fall , saving Connor from a group of demons. She is unaware that Connor is Angel's son. Apparently she established an antiquities business after her departure from the LAPD, and has been using her business connections to learn more about the supernatural and the occult, as well as stocking her hideout with an arsenal of weapons, from ancient to modern. She is last seen leaving to blow up a demon army, so her survival is uncertain. This actual event takes place the same night as "Not Fade Away."
Kate can be seen on one of the known covers of After the Fall #17, along with many of other Team Angel members, and allies. She appears in the same red jacket as is 'First Night', and holding a very large type of gun.
Kate will be seen in Angel: Aftermath, the story of what happens after Angel: After the Fall. She can be seen on the cover of Angel: Aftermath Issue 20, fighting a demon in a tight, black suit, with two stakes at her side.
Angel Season 1
- Lonely Hearts
- I Fall to Pieces
- Rm w/a Vu
- Sense & Sensitivity
- I've Got You Under My Skin
- The Prodigal
- To Shanshu in L.A.
Angel Season 2
Angel: After the Fall
- "First Night" Part 2