Can you detect if a player doesn't have a bool value?

I'm trying to make a murder mystery game to see if I can do it but I want to do that the murder doesn't become the sheriff too, I wrote a code but it won't work, Can anyone help me?

Module script:

local functions = {}

local serverStorage = game:GetService("ServerStorage")
local sword = serverStorage:WaitForChild("Assets"):WaitForChild("ClassicSword")
local gun = serverStorage:WaitForChild("Assets"):WaitForChild("HyperlaserGun")

functions.chooseRandomSherrif = function()
	local players = game:GetService("Players"):GetPlayers()
	local Sherrif = players[math.random(1,#players)]
	local clonedGun = gun:Clone()
	local sherrifTag = Instance.new("BoolValue")
	if Sherrif:WaitForChild("Murder") then
		sherrifTag.Name = "Sherrif"
		sherrifTag.Parent = Sherrif.Character
	
		clonedGun.Parent = Sherrif.Backpack
	end
end

functions.chooseRandomMurder = function()
	local players = game:GetService("Players"):GetPlayers()
	local Murder = players[math.random(1,#players)]
	local clonedSword = sword:Clone()
	local murderTag = Instance.new("BoolValue")
	
	if not Murder:WaitForChild("Sherrif") then
		murderTag.Name = "Murder"
		murderTag.Parent = Murder.Character
	
		clonedSword.Parent = Murder.Backpack
	end
end

return functions

Here's a better idea, use attributes. They're a new feature that are pretty much the replacement for value objects.

An example of how you can fit this into your game:

function AssignSherrif()
	local Player
	repeat
		Player = Players:GetChildren()[math.random(0,#Players:GetChildren())]
	until
		not Player:GetAttribute("Role") = "Murderer"
	Player:SetAttribute("Role", "Sherrif")
	-- other stuff
end

function AssignMurderer()
	local Player
	repeat
		Player = Players:GetChildren()[math.random(0,#Players:GetChildren())]
	until
		not Player:GetAttribute("Role") = "Sherrif"
	Player:SetAttribute("Role", "Murderer")
	-- other stuff
end

This:

if not player.BoolValue then
 	--some code
end