|“||No self-respecting cop wants to have his arse kicked by some broad with a posh British accent.||”|
— SSA Joyner
Kate had dual citizenship; her father was British and her mother American. She eventually became an investigator for Scotland Yard and made a reputation for herself. At some point during her time there, she liaised with Hotch, with whom she later became good friends. Sometime later, she left Scotland Yard to work for the FBI and eventually obtained a high position at its New York office.
Lo-Fi (Part 1)
When the New York Terrorist Cell were posing as a serial shooter, a joint FBI-NYPD task force led by Kate to catch him was formed after the fourth murder. After the fifth, she calls Hotch personally and requests the BAU's assistance. At some point during the investigation, Kate is threatened with being fired if she doesn't solve the case. It is then revealed that Morgan is at the top of the list to replace her. After the sixth murder, Morgan suggests that the NYPD place officers on the streets near certain key areas, like express stops, a suggestion Kate rebuffs, telling him that the BAU is only called to deliver to profile.
When the seventh murder takes place at one of the locations suggested by Morgan, there is a brief argument between him and Hotch, which is quickly mended by Rossi. Upon the discovery that there are at least three different shooters, Kate has the BAU members, as well as NYPD officers, patrol the streets. After the eighth murder, after which Detective Cooper of the NYPD is shot and injured, Rossi and Reid realize that the shootings were the groundwork for a terrorist attack. Kate and Hotch are about to get into an FBI SUV when a bomb placed under it is detonated by one of the terrorists, injuring Hotch and mortally wounding Kate.
Mayhem (Part 2)
As Kate lay bleeding on the street, emergency personnel are parked behind a barricade; they were ordered to wait for the area to be cleared. Eventually, a paramedic (another one of the terrorists), drives to the site, picks Kate and Hotch up, and drives them to a nearby hospital. They find out that the hospital is closed as a government official is in surgery there, but Hotch manages to convince the Secret Service agent to let the ambulance in. Kate is taken into surgery while Hotch and the rest of the BAU realize that whoever is in surgery, as well as the hospital itself, is the terrorists' actual target. Morgan takes the ambulance, which contains a bomb, and drives it to an open lawn where it detonates without injuring anyone. Meanwhile, the rest of the team hunt down the paramedic. Upon finding him, the paramedic slashes his own throat to avoid capture. During this time, Kate dies in surgery, despite the doctors' best efforts.
- JJ noted that Kate bears a striking resemblance to Hotch's ex-wife Haley.
- It is hinted that Hotch and Kate might have become attracted to one another during the case, but as Kate is now dead, nothing has been made out of it.