If Riverdale season 1 was a “whodunit?” then season 2 is definitely a “who is doing it?” as the gang continue their mission to unmask the Black Hood Killer. Betty has been taking the lead on the investigation after she discovered that her speech at the end of the first season inspired one of the men in attendance to take it upon himself to cleanse Riverdale by killing (or attempting to kill) those he deemed sinners. And who knows more about sinners than Riverdale's own Sheriff Keller?
In episode 6 the Black Hood Killer murdered Mr Phillips, Jughead’s high school teacher, who led a secret life as a drug dealer called the Sugarman. The murder took place in the Riverdale police station, supporting the popular fan theory that Sheriff Keller is the serial killer. Keller had access to the jail cell where Phillips was being kept, he has green eyes like the Black Hood, and he also knows a lot about Betty. She and his son, Kevin Keller, have been friends since they were kids, so the Sheriff may well have known about her love of the Nancy Drew books.
In episode 7, “Tales from the Dark Side,” Betty becomes convinced that the Sheriff could be the Black Hood as she lies in bed with Jughead. She keeps her qualms quiet until midway through the episode, when Kevin tells her that his dad keeps sneaking out late at night. Betty immediately shares with Veronica her belief that the Sheriff could be the killer, though Ronnie thinks he’s having an affair while his wife away in Bahrain. It turns out the latter was true, as the two pals spot him meeting Mayor McCoy at a motel room and kissing her passionately.
This revelation does clear some of the suspicion from Sheriff Keller, since practising adultery doesn't exactly fit with the Black Hood's disdain for sinners. However, we’re dealing with a person who thinks he’s justified in committing murder in order to make Riverdale less sinful, so his moral compass is obviously way off. Being the Sheriff would certainly make it easier for him to get away with murder. Keller has an excuse for keeping an eye on the "sinners" of Riverdale, and he's in a position to destroy or alter incriminating evidence. Since he represents the law, no one would expect him to be the killer - except Betty, of course. Yet even Betty seems to change her mind about his guilt after witnessing him kissing the Mayor.
If the writers are being tricky and trying to lure us into a false sense of security about Keller, they really laid it on thick in "Tales From the Dark Side." Not only did the affair reveal imply that the Sheriff was not the Black Hood, but the introduction of Tony Todd’s Farmer McGinty draws the audience's attention to another possibility: The Riverdale Reaper. McGinty tells Jughead that a few years ago more gruesome murders took place when a man killed an entire family with a shotgun:
"There was a family living out near the Fox Forest. A good family. Mother. Father. Two kids. One night, they were all asleep when someone broke in. A Bogeyman who went room to room with a shotgun, shot ‘em all dead. No survivors."
The farmer says the Reaper never got caught and could still be hanging around Riverdale, which leads Jughead to believe that maybe he could be behind the Black Hood killings too. In this week's episode, "The House of the Devil," we learned that the Riverdale Reaper left one survivor: a third child, who grew up to be Riverdale High School janitor Mr. Svenson. Svenson himself became a suspect after this discovery, but Archie ultimately "cleared" him, confident that Svenson's eyes do not match the Black Hood.
Who knows, maybe McGinty is the Black Hood killer. He seemed pretty volatile when Jughead refused to pay him anymore money, and he’s a fan of a religious radio station that seems to think the Black Hood is doing God’s work. It would certainly be a nice touch if the farmer turned out to be the killer, as Todd is most famous for his terrifying titular role in the Candyman franchise. However, from the looks of things the Black Hood is a white man with green eyes so it seems unlikely that McGinty is the killer. Maybe he's just a fan.
The Black Hood's green eyes and knowledge of Betty’s childhood also mean that Hal Cooper is in the mix as a prime suspect. He also knew of Miss Grundy and Archie’s affair, as well as Polly’s location, and he does have a creepy vibe. However, the Black Hood may actually be more than one person.
Keller said that two notes meant to be from the killer looked like they were written by different people, which means someone could be acting the copycat of the real Black Hood. This potentially could be Hiram Lodge, sinceit was weird that the Hood refused to kill Nick St. Clair because he wasn’t a “son of Riverdale,” but has no problem killing another Riverdale outsider - Miss Grundy. Lodge’s affiliation to St. Clair’s parents would be a good enough reason to not murder their son on his front doorstep, but that doesn’t mean he couldn’t have committed other murders for personal gain.
Riverdale is certainly playing a good game of keeping us on our toes about the Black Hood’s identity. Though it might seem that Sheriff Keller's strange behavior is explained away by the fact that he's having an affair, that could just be a trick to try and make the audience dismiss him as a suspect. Is Sheriff Keller taking his mission to punish law-breakers a little too seriously? We may find out for sure next week, in Riverdale's midseason finale.