Kate Joyner

"No self-respecting cop wants to have his arse kicked by some broad with a posh British accent."

SSA Kate Joyner is a notable character who appeared in Lo-Fi and Mayhem.

Background
Kate has a dual citizenship; her father was British and her mother American. She eventually became a Scotland Yard investigator and made a reputation for herself. At some point during her time there, she liased with Hotch with whom she later became friends. Some time later, she left Scotland Yard to work for the FBI and eventually obtained a high position at its New York office.

Lo-Fi
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 called Hotch personally and requested the BAU's assistance. At some point during the investigation, Kate was threatened with being fired if she didn't solve the case. It was then revealed that Morgan was at the top of the list to replace her. After the sixth murder, Morgan suggested that the NYPD place officers on the streets near certain key areas, like express stops. When the seventh murder took place at one of the locations suggested by Morgan, there was a brief argument between him and Hotch, which was quickly mended by Rossi. Upon the discovery that there were at least three different shooters, Kate had the BAU members as well as NYPD officers patrol the streets. After the eighth murder, after which Detective Cooper of the NYPD was shot and injured, Rossi and Reid realized that the shootings were the groundwork for a terrorist attack. Kate and Hotch were about to get into an FBI SUV when a bomb placed under it was detonated by one of the terrorists, injuring Hotch and fatality wounding Kate.

Mayhem
As Kate lay bleeding on the street, emergency personnel were parked behind a barricade; they had been ordered to wait for the area to be cleared. Eventually, a paramedic (another one of the terrorists), drove to the site, picked Kate and Hotch up, and drove them to a nearby hospital. They found out that the hospital was closed as a government official was in surgery there, but Hotch managed to convince the Secret Service agents to let the ambulance in. Kate was taken into surgery while Hotch and the rest of the BAU realized that the hospital was the terrorists' actual target. Derek took the ambulance, which contained a bomb, and drove it to an open lawn where it was detonated without injuring anyone. Meanwhile, the rest of the team hunted down the paramedic. Upon finding him, the paramedic slit his own throat to avoid capture. During this time, Kate died in surgery, despite the doctors' best efforts.

Appearances

 * Season Three
 * Lo-Fi
 * Season Four
 * Mayhem