The Riverdale Season 4 midseason finale (Episode 9) delivered a characteristic twist in the form of a flash-forward that appeared to show Betty Cooper (played by Lili Reinhart) killing Jughead Jones (Cole Sprouse) with a rock.
Of course, this being Riverdale, despite the fact we have seen Jughead's lifeless body not once but twice this season, fans are skeptical that Betty really killed him—after all, this would not be the first time The CW show has tried to make us believe one of its characters was dead.
All the clues Betty DID kill Jughead
What we actually saw
If Betty was on trial for killing Jughead, then the fact that she was found with a rock in her hand standing above his corpse would be pretty damning evidence. Plus, it fits with the other flash-forwards we have seen. In the scene, Archie Andrews (KJ Apa) and Veronica (Camila Mendes) finds Betty with the rock and asks what she has done. As in the other scenes we have seen Archie, Veronica and Betty covered in blood and then in a line-up in the police station, the show seems to be suggesting that they cover up Jughead's death and then get caught in the act.
The 'serial killer gene'
A running theme of Riverdale Season 4 is the "serial killer gene" that Betty seemingly has, inherited from her father "The Black Hood." Whether she does or does not have this gene (or whether such a gene actually exists) has never been fully answered in the show, but this could be Riverdale telling us that the back half of Season 4 will see "Dark Betty" finally on the prowl.
Post-hypnotic suggestion
Riverdale Season 4, Episode 9 revealed that the rest of the Coopers had been brainwashed by The Farm to try and kill Dark Betty every time they hear the word "tangerine" said three times. Though Charles Smith (Wyatt Nash) ostensibly helped Betty to kill her dark self in her mind, this may not have fully worked and has actually allowed Dark Betty to become dominant in her personality.

The coroner's scene
Though Riverdale has cried wolf too many times for all of its fans to ever believe that Jughead is really dead (more on that below), a scene like the one in Riverdale Season 4, Episode 4 would be pretty conclusive in any other show. In that episode, we saw Jughead on a slab in the coroner's office, suggesting he is well and truly gone.
All the clues Betty DID NOT kill Jughead
This is Riverdale
If Jughead is not dead, this would not be the first time the show tried to make us believe a major character was dead—in fact, it would not even be the first time that the series has tried to make us believe that Jughead was dead. In this show, a crazy fan theory like identical twins, cult brainwashing or hypnotism-based murder is always far more likely than the simple explanation for an event.
We did not actually see the act
It has become something of a TV cliche, but one that has developed because it is so often true: If you do not see a character being killed, then they are probably not dead. Though Riverdale has slightly bent this trope by showing us Jughead's body twice, it only showed Betty with a rock in her hand rather than actually hitting her boyfriend, which could suggest all manner of twists, like perhaps she is being set up by ex-members of The Farm or by Stonewall Prep students with a grudge against Jughead.

The 'no emotion' fan theory
Viewers of these flash-forwards have pointed out that the various characters who we see in the coroner's office or in other scenes dealing with the death of Jughead seem to be insufficiently emotional over what should be the devastating demise of their friend/lover/son. Although this could just be Riverdale fans inadvertently throwing shade at the actors on The CW show, it could also be a hint that they all know that Jughead is not really dead, and are covering for him while he fakes his own death.
Cole Sprouse has not said he is leaving Riverdale
Other fans have pointed out that there has been no sign that Cole Sprouse is leaving Riverdale, suggesting that his character is going nowhere. In this world of spoilers, fans just cannot believe that Jughead could leave the show without it being spoiled.
However, with the latest flashback revealing that whatever happened to Jughead happened just four weeks after where we currently are in the timeline, it seems that we will finally get all the answers when Riverdale returns in 2020.
Riverdale Season 4 returns in January 2020 to The CW.