Murderer

It's dark outside
And the air is cold
Inside isn't much better
Or so I've been told
Of a killer amoung us
The attack wasn't heard
No screaming, no stabbing
How absurd
But then there's a body
Her name was Lisa Marie
I'll find her killer
And wave my usual fee
In a pool of blood
A dagger was found
No body move
Don't make a sound
I conclude this happened in cold blood
Now there's one thing left to do
Time to unmask the mad man
The killer is . . .
YOU!