Witch Creek Road S3 E16 Explained (Spoilers)
We begin with Keifer on the phone with the police, who want the group to stay put while they send an officer out to the motel. Jay expresses his concern; he doesn't want to stay. At this, Kevin comes out of the office holding a gun he found in the back room of the office. He points it at Jay and asks, “If I shot you, would we see blood or bugs?” Keifer suggests that maybe he should be the one to hold the gun, and Kevin relinquishes it to Keifer.
Kevin asks what the plan is. Keifer acknowledges that, while some of them want to leave, the car's not starting. “[They] can't go anywhere, even if [they] wanted to.” Instead, he suggests they "hole up in [their hotel] room and wait for the police.”
In the hotel room, Kevin observes, “Am I the only one concerned over the fact that we're the only people at this motel? I swear, when we arrived last night, there were more people here. The car also concerns me.”
The police officer arrives and walks into the motel's office. Jay leaves the room to get him – however, when he looks into the office, he sees the officer talking to Edwin. Jay rushes back to the room, telling everyone to get inside. “I think [the officer's] been infected,” he says.
The officer comes to their room, and Keifer lets him in. Meanwhile, Kevin is hiding behind the door and hits the officer over the head with a lamp. The officer falls to the floor, unconscious. Both Jay and Kevin reach for the officer's gun, but Kevin is faster.
Kevin says, “We should check [the officer] for bugs.” Jay replies, “It's too soon. If the cop is infected, it only just happened.” This agitates Kevin, who replies, “What do you mean “if”?! You said he was infected!” Jay replies that he thought he was infected.
Kevin accuses Jay of setting him up. Jay rolls his eyes, saying, “Yes, Kevin, I set you up. It's all part of my “master” plan.” At this, Kevin shoots Jay.
THE RELATIONSHIP OF KEVIN AND JAY: Kevin and Jay were, prior to recent events, best friends. The problem is, being best friends, they also know how to best get under each other's skin.
By the beginning of this episode, it's safe to say neither one trusts the other - but it should also be noted that, despite Kevin's paranoia and distrust of Jay, he still lets Keifer take the gun from him. This is a moment of hope for Kevin. That is, he's not so far down the rabbit hole of paranoia that he's unwilling to give up the gun.
With that said, he's unwilling to let Jay have a gun, so when the police officer drops his gun, he makes sure to grab it before Jay can. This also leads to Jay's premature death, as he misjudges how Kevin will react to his sarcasm and ends up getting shot.