The season 4 finale of The Handmaid's Tale ends with a cathartic act of revenge, but is June under arrest for helping kill Fred Waterford? The episode shows June being forced to grapple with the fact that Fred and Serena might get away with their crimes. Fred is working as an intelligence asset for the Canadian government and the new, privileged treatment is going to Serena's head.
Fred and Serena are malevolent in their own specific ways. June seems to hate Serena more because she's always seemed to have more of a grasp on the moral reprehensibility of the Waterfords' behavior in Gilead. Yet, in order to get what she wants, Serena will swiftly push any concerns that bubble up to the side. Fred, on the other hand, seems more blissfully ignorant in the sense that he truly believes in Gilead's ways and doesn't seem to grasp the weight of the couple's culpability in a slew of heinous behaviors.
It's Fred's distorted view of reality and the past that seems to finally push June over the edge, prompting her to manipulate him into a false sense of security during their meeting. Of course, the biggest bombshell in the episode is delivered later with Fred's brutal death in No Man's Land at the hands of June and other ex-Handmaids. When June returns home at the end of The Handmaid's Tale's season 4 finale, still covered in blood from the killing, she's eerily at peace. Poor Luke, on the other hand, is horrified when he finds her holding Nichole in the nursery in such a state. But the precise reasoning for why he seems so aghast and sinks back against the wall isn't explicitly conveyed. He immediately grasps the reality of what's happened, but it's unclear as to whether or not June is in hot water legally and his reaction is because he knows June will have to legally pay for her crime. June herself seems to understand the likely outcome of her new situation, as she immediately says to Luke, "I know. I'm sorry," and asks for a few minutes with Nichole before she goes.
At the moment, it doesn't appear that June is in any confirmed trouble with the law–at least, not yet. Surely, now that everyone knows Fred Waterford has been traded back to Gilead and Serena has been sent his finger in the mail, it won't take long for the authorities to connect the dots as to who's probably behind his death. It's more likely that June and Luke are both aware of the situation's easily identifiable motivations, hence Luke's shock and horror (in addition to the fact that she's murdered someone) and June's seeming awareness that she doesn't have much time with little Nichole. She seems to know she'll either have to turn herself in or there will be a knock on the door in no time.
As June says earlier in the finale, she's been looking for a way to finally let Fred go and move on with her life. But the rage and anguish she hasn't been able to put away are completely justified and understandable. Her craving for revenge is also quite understandable given everything she's been through. As Commander Lawrence warned her earlier in the Handmaid's Tale episode, however, whatever punishment she cooks up for Fred Waterford will never truly be enough to satisfy or heal her and he's most likely right. Hopefully, when the series returns, June can somehow evade prosecution from the very justice system that has so recently failed her and she can begin to truly find the solace she seeks.