The Flash season 7 addresses the past crimes that Killer Frost committed in the past seasons when she was still a super-villain. In the last few seasons of the Arrowverse drama, Killer Frost has gone in a more heroic direction as she and Caitlin Snow began being on the same page. Originally, Caitlin wasn't a metahuman until The Flash season 3 Flashpoint event rewrote her Arrowverse history. But The CW iteration of the ice villain has been depicted slightly differently from the source material. In this version, Caitlin and Killer Frost are two separate personas who share the same body.
As of The Flash season 7, Killer Frost and Caitlin have officially separated and exist as two individuals. While the scientific explanation was slightly hard to grasp, something caused it to happen after Killer Frost took on Mirror Master. But before they got along, Killer Frost was an entity that Caitlin was trying to hold back when her powers began emerging in the third season. The more she used her ice abilities, the less control Caitlin would have in preventing her transformation into the villainess. Despite Frost having shifted into a hero, that didn't erase her past criminal actions.
The Flash season 7 recently introduced Kristen Kramer, who wanted to arrest Killer Frost for her crimes on behalf of the Governor's Municipal Logistics Commission. In the seventh episode, "Growing Pains," Killer Frost initially gets framed for an ice attack at Ivo Labs that Chillblaine orchestrated. While Killer Frost manages to clear her name on that front, she eventually stops running from the authorities and gives herself over to begin paying for her sins. When Killer Frost was on a dark path, she did break several laws, with Cecile Horton referencing several of them in The Flash's "Growing Pains."
Aggravated Assault On Doctor Alchemy's Follower
When Caitlin's Killer Frost persona was beginning to get stronger in the first half of The Flash season 3, she initially tried to remove her powers. Caitlin, as Killer Frost, sneaked into an interrogation room with one of Doctor Alchemy's followers. While Wally West was in his cocoon, Killer Frost went to Central City Police Department and lied to Joe West that his son had recovered so she could be alone with the follower. As the follower refused to tell Killer Frost where to find Doctor Alchemy, she lashed out and hurt him. Despite CCPD officers trying to stop her, Killer Frost managed to get out of the interrogation room and locked the cops from the outside. Even though Killer Frost had destroyed the security camera, this is the first count that Cecilie brings up in "Growing Pains."
Kidnapping Julian Albert & Threatening To Kill Him
In The Flash season 3, episode 7, "Killer Frost," the Alchemy acolyte wasn't the only person she ended up hurting. Right as Killer Frost tried to escape, Julian Albert witnesses her locking in the officers. That led to Julian getting kidnapped by Killer Frost, who forced him to help her find Doctor Alchemy. Killer Frost took Julian to a frozen food warehouse where she demanded that he locate more of Doctor Alchemy's followers in Central City. While Killer Frost didn't kill him, she threatened to take his life if he didn't do as she said. Julian survives but still ended up hurt as Killer Frost used her abilities on one of his wrists, resulting in frostbite. Despite Julian initially not telling the cops who kidnapped him during The Flash season 3, Cecile revealed to Frost that taking him hostage was another count on her list.
Attempted Murder At Tracy Brand
In the second half of The Flash season 3, Caitlin eventually got consumed by the Killer Frost persona, who served Savitar. In the twentieth episode, "I Know Who You Are," Killer Frost tried to murder Tracy Brand, who became a temporary member of Team Flash. After The Flash learned from his future self that at some point, Tracy helped them trap Savitar in the Speed Force. That's why Savitar, in the present time, needed her taken out before Team Flash could get to her. When the team found her at Central City University, Killer Frost was already there as she tried to murder Tracy. Had it not been for Barry Allen, Killer Frost would have succeeded in ending Tracy's life. That was, however, just one of two murder attempts at Tracy as Killer Frost also tried one more time when she located Tracy at Jitters with H.R.
Kidnapping & Threatening To Murder Cecile Horton
While The Flash managed to keep Tracy safe, Killer Frost didn't stop trying in "I Know Who You Are." When she failed to kill Tracy the first time around, Killer Frost decided to go after Cecile when she was still Central City's district attorney. Killer Frost went to Joe's home and kidnapped Cecile, threatening to slice her throat if Joe tried to shoot. As she took her hostage, Killer Frost promised Joe that unless he turned Tracy over to her, she would kill Cecile. Eventually, Team Flash managed to save Cecile from Killer Frost without having to give up Tracy. Vibe did have a confrontation with Killer Frost, who tried to murder Cisco for the second time during "I Know Who You Are." Even though Cecile didn't bring up the murder threat, it's not forgotten that Killer Frost did threaten her life nonetheless.
Kidnapping & Assistance To Attempted Murder At Iris West
The Flash season 3 centered mostly on Barry fighting against a ticking clock to prevent Iris West's death from happening on May 23, 2017. In the final two episodes of the season, Iris eventually got taken by Savitar the night she's about to die on Infantino Street. After H.R. accidentally revealed to Savitar that Iris was hiding on Earth-2, he wanted to make amends and tried rescuing her. H.R. almost succeeds before Savitar and Killer Frost noticed what he was trying to do. Realizing that they couldn't outrun Killer Frost, H.R. used his facial transmogrification tool to disguise himself as Iris while she got his looks. "Iris" managed to convince Killer Frost to let "H.R." go as he got taken by the ice villain back to Savitar. Not only was Killer Frost guilty of helping Savitar keep the real Iris prisoner, but she was also responsible in the assistance of getting H.R. (as Iris) murdered. Had it not been for H.R., Killer Frost would have also been guilty of assisting Savitar with the murder of Iris.
Working For Amunet Black & Assisting Meta-Human Trafficking
While Cailtin tried to find herself, Killer Frost still got herself in trouble at the start of The Flash season 4. Several months after Barry went into the Speed Force, Caitlin and Killer Frost became involved with Amunet Black's criminal activities. Not only did Killer Frost become one of Amunet's favorite henchmen, but she would aid the crimelord's meta-human trafficking operations as her muscle. As Killer Frost, she would get assignments to go after Amunet's enemies and make them lose their toes and fingers. Both Caitlin and Killer Frost are guilty of assisting Amunet's meta-human trafficking ring.
Before she tried to quit, Killer Frost stood by as one meta-human after another got exposed to the meta-human black market thanks to Amunet. Whether or not that was on Killer Frost's list of crimes has yet to be clarified in The Flash season 7. It wouldn't be shocking if Caitlin and Killer Frost's involvement with Amunet is something that does get brought up, among other criminal charges too. While this is happening several seasons later, The Flash still gets props for actually addressing that Killer Frost did cause a lot of harm before turning over a new leaf.
It's better later than never that The Flash gets to the bottom of it because, despite her heroic actions in the recent seasons, the show never highlighted Killer Frost's crimes on a massive scale. Depending on how Killer Frost's trial goes, The Flash might be about to write her out of the series temporarily or maybe even for good. Following their body split, it's hard to imagine that Danielle Panabaker would continue to play two characters for the rest of the season as well as in The Flash season 8 and beyond. Only time will tell how this will end, but it would be awkward if somehow, after all this trouble, The Flash's ongoing storyline concluded with Killer Frost walking free.