Nilsine was sitting infront of the fireplace and her mother Tova was sleeping in the room next to us with no possible visual vantage point of Nilsine and me.
I talked to Nilsine and told her that a certain person is not happy with her.
Then I killed her with a dagger while standing... and got a bounty.
I looked to see if Tova was awake and had somehow seen me but she wasn't.
Then a guard rushes in.
Nilsine, Tova, and me were the only people in the house.
Tova was asleep and in another room making it impossible for her to have witnessed the murder.
It just doesn't make sense... I mean, do the guards have some sort of hidden camera planted on the Dragonborn or something?
Is Tova able to see through walls and use some sorta walkie-talkie to inform Guards of a murder?
It's the same with any murder that occurs.
If you were to snipe someone in Whiterun market place while completely hidden with all the right perks and buffs then the guards would still be alerted and go after you specifically even though no one saw you commit the crime.
It's the same with planting poison in an npc's pocket and killing them with people around but completely hidden.